573 research outputs found
Эволюция рассмотрения проблемы сознания в исследованиях российской философии советского периода (Выготский, Ильенков, Мамардашвили)
The document analyzes provisions of the culture-historical concept of L.S. Vygotsky concerning genesis and structure of thinking pertaining to the ideas of I.E. Ilyenkov and M.K. Mamardashvili, leading philosophers of the Soviet era.В статье дается анализ положений культурно-исторической концепции Л.С. Выготского, касающихся генезиса и структуры мышления, в соотнесении с идеями ведущих философов советской эпохи - Э.В. Ильенкова и М.К. Мамардашвили
Radiation from an oscillator uniformly moving along the axis of a dielectric cylinder
The radiation generated by a charged longitudinal oscillator moving with a
constant drift velocity along the axis of a dielectric cylinder immersed in a
homogeneous medium is investigated. For an arbitrary oscillation law a formula
is derived for the spectral-angular distribution of this radiation. Under the
Cherenkov condition for the dielectric permittivity of the external medium and
oscillator drift velocity this formula contains two summands. The first one
corresponds to the radiation with a continuous spectrum which propagates at the
Cherenkov angle of the external medium. The second one describes the radiation
which has a discrete spectrum for a given angle of propagation. The
corresponding frequencies are multiples of the Doppler-shifted oscillation
frequency. The results of numerical calculations for the angular distribution
of the radiated quanta are presented and they are compared with the
corresponding quantities for the radiation in a homogeneous medium. It is shown
that the presence of the cylinder can increase essentially the radiation
intensity.Comment: 16 pages, 8 EPS figure
The effect of hydrogen on the magnetostriction of rare-earth compounds TbxDy₁₋xFe₂
The crystal structure and the magnetic and magnetoelastic properties of TbxDy₁₋xFe₂Hy (x = 0.27; 0.41; y ≤ 3) are investigated. The hydrides are obtained by the interaction of TbxDy₁₋xFe₂ samples with hydrogen gas at room temperature. It is established that the hydrides have the same cubic type of structure as the parent compounds but the lattice parameter in the hydrides is larger than in the hydrogen-free samples. Both the Curie temperature and the magnetic moment decrease drastically as the hydrogen concentration increases. Measurements of the longitudinal λ|| and transverse magnetostriction λ^ are carried out in magnetic fields up to 12 kOe in the temperature range 78√300 K using strain gauges.The thermal expansion coefficients as a function of temperature are obtained for hydrides with high hydrogen concentration. The magnetostriction of hydrides is strongly different from that of hydride-free samples. The small and negative value of the magnetostriction at low temperatures proves that hydrogen atoms make a strong contribution to the crystal field acting on the rare-earth ions
Polynomial Lie algebra methods in solving the second-harmonic generation model: some exact and approximate calculations
We compare exact and SU(2)-cluster approximate calculation schemes to
determine dynamics of the second-harmonic generation model using its
reformulation in terms of a polynomial Lie algebra and related
spectral representations of the model evolution operator realized in
algorithmic forms. It enabled us to implement computer experiments exhibiting a
satisfactory accuracy of the cluster approximations in a large range of
characteristic model parameters.Comment: LaTex file, 13 pages, 3 figure
Radiative corrections to radiative \pi e 2 decay
The lowest order radiative corrections (RC) to width and spectra of radiative
decay are calculated. We take into account virtual photon emission
contribution as well as soft and hard real photon emission one. The result
turns out to be consistent with the standard Drell-Yan picture for the width
and spectra in the leading logarithmical approximation which permits us to
generalize it to all orders of perturbation theory. Explicit expressions of
nonleading contributions are obtained. The contribution of short distance is
found to be in agreement with Standard Model predictions. It is presented as a
general normalization factor. We check the validity of the
Kinoshita-Lee-Nauenberg theorem about cancellation in the total width of the
mass singularities at zero limit of electron mass. We discuss the results of
the previous papers devoted to this problem. The Dalitz plot distribution is
illustrated numerically.Comment: 21 pages, 3 figures, 3 tables; a table with K-factor values was adde
On the analysis of the pi -> e nu gamma experimental data
The most general amplitude for the radiative pion decay pi -> e nu gamma
including terms beyond V-A theory is considered. The experimental constraints
on the decay amplitude components are discussed. A model independent
presentation of the results of high statistics and high resolution experiments
is suggested.Comment: 5 pages, 2 figure
Measurement of and between 3.12 and 3.72 GeV at the KEDR detector
Using the KEDR detector at the VEPP-4M collider, we have measured
the values of and at seven points of the center-of-mass
energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or
better than at most of energy points with a systematic uncertainty of
about . At the moment it is the most accurate measurement of in
this energy range
New precise determination of the \tau lepton mass at KEDR detector
The status of the experiment on the precise lepton mass measurement
running at the VEPP-4M collider with the KEDR detector is reported. The mass
value is evaluated from the cross section behaviour around the
production threshold. The preliminary result based on 6.7 pb of data is
MeV. Using 0.8 pb of data
collected at the peak the preliminary result is also obtained:
eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton
Physics, Tau0
Measurement of \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-) and \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)
The products of the electron width of the J/\psi meson and the branching
fraction of its decays to the lepton pairs were measured using data from the
KEDR experiment at the VEPP-4M electron-positron collider. The results are
\Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-)=(0.3323\pm0.0064\pm0.0048) keV,
\Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)=(0.3318\pm0.0052\pm0.0063) keV.
Their combinations
\Gamma_{ee}\times(\Gamma_{ee}+\Gamma_{\mu\mu})/\Gamma=(0.6641\pm0.0082\pm0.0100)
keV,
\Gamma_{ee}/\Gamma_{\mu\mu}=1.002\pm0.021\pm0.013 can be used to improve
theaccuracy of the leptonic and full widths and test leptonic universality.
Assuming e\mu universality and using the world average value of the lepton
branching fraction, we also determine the leptonic \Gamma_{ll}=5.59\pm0.12 keV
and total \Gamma=94.1\pm2.7 keV widths of the J/\psi meson.Comment: 7 pages, 6 figure
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