242 research outputs found
Two dimensional electron gas driven by strong alternating electric field
2D Fermi liquid driven by uniform alternating electric field at zero
temperature may remain in quantum coherent non-equilibrium state. We develop a
quasistatic approximation for strong and slow ac-fields and solve the problem
of driven disordered 2D electron gas in high non-overlapping Landau levels. The
broadening of Landau level has the Lorentz form and is inversely proportional
to the amplitude of the ac-field. In the absence of electron-phonon interaction
the electron distribution function is constant within the last Landau level and
the diagonal dc-conductivity is zero. For weak electron-phonon interaction the
dc-conductivity is anisotropic. A kinetic transition from the phonon cooling to
the phonon heating is predicted.Comment: 8 pages, 1 figure REVTE
Relativistic Heavy--Ion Collisions in the Dynamical String--Parton Model
We develop and extend the dynamical string parton model. This model, which is
based on the salient features of QCD, uses classical Nambu-Got\=o strings with
the endpoints identified as partons, an invariant string breaking model of the
hadronization process, and interactions described as quark-quark interactions.
In this work, the original model is extended to include a phenomenological
quantization of the mass of the strings, an analytical technique for treating
the incident nucleons as a distribution of string configurations determined by
the experimentally measured structure function, the inclusion of the gluonic
content of the nucleon through the introduction of purely gluonic strings, and
the use of a hard parton-parton interaction taken from perturbative QCD
combined with a phenomenological soft interaction. The limited number of
parameters in the model are adjusted to and -- data. Utilizing
these parameters, the first calculations of the model for -- and
-- collisions are presented and found to be in reasonable agreement with
a broad set of data.Comment: 26 pages of text with 23 Postscript figures placed in tex
Influence of Rotation on Pulsar Radiation Characteristics
We present a relativistic model for pulsar radio emission by including the
effect of rotation on coherent curvature radiation by bunches. We find that
rotation broadens the width of leading component compared to the width of
trailing component. We estimate the component widths in the average pulse
profiles of about 24 pulsars, and find that 19 of them have a broader leading
component. We explain this difference in the component widths by using the
nested cone emission geometry.
We estimate the effect of pulsar spin on the Stokes parameters, and find that
the inclination between the rotation and magnetic axes can introduce an
asymmetry in the circular polarization of the conal components. We analyze the
single pulse polarization data of PSR B0329+54 at 606 MHz, and find that in its
conal components, one sense of circular polarization dominates in the leading
component while the other sense dominates in the trailing component. Our
simulation shows that changing the sign of the impact parameter changes the
sense of circular polarization as well as the swing of polarization angle.Comment: 20 pages, 4 Postscript figures, uses aastex.cls. Accepted for
Publication in ApJ 200
Self-Consistent Separable Rpa Approach for Skyrme Forces: Axial Nuclei
The self-consistent separable RPA (random phase approximation) method is
formulated for Skyrme forces with pairing. The method is based on a general
self-consistent procedure for factorization of the two-body interaction. It is
relevant for various density- and current-dependent functionals. The
contributions of the time-even and time-odd Skyrme terms as well as of the
Coulomb and pairing terms to the residual interaction are taken
self-consistently into account. Most of the expression have a transparent
analytical form, which makes the method convenient for the treatment and
analysis. The separable character of the residual interaction allows to avoid
diagonalization of high-rank RPA matrices and thus to minimize the calculation
effort. The previous studies have demonstrated high numerical accuracy and
efficiency of the method for spherical nuclei. In this contribution, the method
is specified for axial nuclei. We provide systematic and detailed presentation
of formalism and discuss different aspects of the model.Comment: 42 page
Overiew of existing solutions excitation H₀₁ wave in the circular waveguide
В данной работе рассмотрены осесимметричная магнитная волна H₀₁ в круглом волноводе, особенности структуры ее поля, возможности применения аномальных свойств волны H₀₁ на практике, кратко рассмотрены существующие способы возбуждения волны Н₀₁ в круглом волноводе такие как: возбуждение с помощью противофазных элементов связи, возбуждение с помощью торцевых щелей связи между прямоугольным и круглым волноводами, преобразование типов волн посредством плавных переходов между волноводами с разными типами волн, возбуждение с помощью цилиндрической щелевой антенны, возбуждение за счет подключения прямоугольного волновода узкой стенкой на закороченный торец круглого волновода. Также рассмотрены пути для получения максимального коэффициента передачи и расширения рабочей полосы устройства возбуждения.In the article axisymmetric magnetic wave H₀₁ in the circular waveguide, features of its field structure, possible implementation of its anomalous characteristics in practical systems are considered. Also existent excitation devices, such as: excitation with antiphased coupling elements, excitation with the frontal slots between rectangular and circular waveguides, modes transformation using taper between waveguides with different modes, excitation using the cylindrical slot antenna, excitation with the rectangular waveguides narrow side on the short-circuited end of the circular waveguide are described. The ways of deriving a maximal coefficient of transmission and widening of the frequency band of the excitation device are proposed
On the nature of radio pulsars with long periods
It is shown that the drift waves near the light cylinder can cause the
modulation of the emission with periods of the order several seconds. These
periods explain the intervals between successive pulses observed in "magnetars"
and radio pulsars with long periods. The model under consideration makes it
possible to calculate the real rotation periods of the host neutron stars. They
are less than 1 sec for the investigated objects. The magnetic fields at the
surface of the neutron star of the order 10^(11)-10^(13) G and equal to the
usual fields for known radio pulsarsComment: 18 pages, 4 figure
On the connection between gamma and radio radiation spectra in pulsars
The model of pulsar radio emission is discussed in which a coherent radio
emis-sion is excited in a vacuum gap above polar cap of neutron star. Pulsar X
and gamma radiation are considered as the result of low-frequency radio
emission inverse Comp-ton scattering on ultra relativistic electrons
accelerated in the gap. The influence of the pulsar magnetic field on Compton
scattering is taken into account. The relation of radio and gamma radiation
spectra has been found in the framework of the model.Comment: 15 pages, 3 figures, Russian version accepted to JETP, partly
published in JETP Letters, Vol. 85, #6 (2007
Optimization of neuropsychological rehabilitation of higher mental functions in junior schoolchildren with mild intellectual disability
The article studies the effectiveness of complex neuropsychological rehabilitative impact on the nonverbal and verbal higher mental functions (HMFs) in junior schoolchildren with mild intellectual disability (ID) in comparison with the impact exclusively on the verbal HMFs in the same category of children.В статье рассматривается эффективность нейропсихологического коррекционного воздействия на невербальные и вербальные высшие психические функции детей младшего школьного возраста с легкой степенью умственной отсталости
Review of scientific topics for Millimetron space observatory
This paper describes outstanding issues in astrophysics and cosmology that
can be solved by astronomical observations in a broad spectral range from far
infrared to millimeter wavelengths. The discussed problems related to the
formation of stars and planets, galaxies and the interstellar medium, studies
of black holes and the development of the cosmological model can be addressed
by the planned space observatory Millimetron (the "Spectr-M" project) equipped
with a cooled 10-m mirror. Millimetron can operate both as a single-dish
telescope and as a part of a space-ground interferometer with very long
baseline.Comment: The translation of the original article in Physics Uspekhi
http://ufn.ru/ru/articles/2014/12/c
Nuclear Scissors Mode with Pairing
The coupled dynamics of the scissors mode and the isovector giant quadrupole
resonance are studied using a generalized Wigner function moments method taking
into account pair correlations. Equations of motion for angular momentum,
quadrupole moment and other relevant collective variables are derived on the
basis of the time dependent Hartree-Fock-Bogoliubov equations. Analytical
expressions for energy centroids and transitions probabilities are found for
the harmonic oscillator model with the quadrupole-quadrupole residual
interaction and monopole pairing force. Deformation dependences of energies and
values are correctly reproduced. The inclusion of pair correlations
leads to a drastic improvement in the description of qualitative and
quantitative characteristics of the scissors mode.Comment: 36 pages, 5 figures, the results of calculation by another method and
the section concerning currents are adde
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