2,482 research outputs found
The self-consistent field model for Fermi systems with account of three-body interactions
On the basis of a microscopic model of self-consistent field, the
thermodynamics of the many-particle Fermi system at finite temperatures with
account of three-body interactions is built and the quasiparticle equations of
motion are obtained. It is shown that the delta-like three-body interaction
gives no contribution into the self-consistent field, and the description of
three-body forces requires their nonlocality to be taken into account. The
spatially uniform system is considered in detail, and on the basis of the
developed microscopic approach general formulas are derived for the fermion's
effective mass and the system's equation of state with account of contribution
from three-body forces. The effective mass and pressure are numerically
calculated for the potential of "semi-transparent sphere" type at zero
temperature. Expansions of the effective mass and pressure in powers of density
are obtained. It is shown that, with account of only pair forces, the
interaction of repulsive character reduces the quasiparticle effective mass
relative to the mass of a free particle, and the attractive interaction raises
the effective mass. The question of thermodynamic stability of the Fermi system
is considered and the three-body repulsive interaction is shown to extend the
region of stability of the system with the interparticle pair attraction. The
quasiparticle energy spectrum is calculated with account of three-body forces.Comment: 21 pages, 5 figure
Validity of abundances derived from spaxel spectra of the MaNGA survey
We measured the emission lines in the spaxel spectra of MaNGA galaxies in
order to determine the abundance distributions therein. It has been suggested
that the strength of the low-ionization lines, R_2, N_2, and S_2 may be
increased (relative to Balmer lines) in (some) spaxel spectra of the MaNGA
survey due to a contribution of the radiation of the diffuse ionized gas.
Consequently, the abundances derived from the spaxel spectra through
strong-line methods may suffer from large errors. We examined this expectation
by comparing the behaviour of the line intensities and the abundances estimated
through different calibrations for slit spectra of HII regions in nearby
galaxies, for fibre spectra from the SDSS, and for spaxel spectra of the MaNGA
survey. We found that the S_2 strength is increased significantly in the fibre
and spaxel spectra. The mean enhancement changes with metallicity and can be as
large as a factor of 2. The mean distortion of R_2 and N_2 is less than a
factor of 1.3. This suggests that Kaufmann et al.'s demarcation line between
AGNs and HII regions in the BPT diagram is a useful criterion to reject spectra
with significantly distorted strengths of the N_2 and R_2 lines. We find that
the three-dimensional R calibration, which uses the N_2 and R_2 lines, produces
reliable abundances in the MaNGA galaxies. The one-dimensional N2 calibration
produces either reliable or wrong abundances depending on whether excitation
and N/O abundance ratio in the target region (spaxel) are close to or differ
from those parameters in the calibrating points located close to the
calibration relation. We then determined abundance distributions within the
optical radii in the discs of 47 MaNGA galaxies. The optical radii of the
galaxies were estimated from the surface brightness profiles constructed based
on the MaNGA observations.Comment: 19 pages, 15 figures, accepted for publication in A&
MOTIVATION OF THE LAWFUL BEHAVIOR OF A PERSON AS A RESULT AND THE PROBLEM OF THE LEGAL EDUCATION
Обґрунтовано можливість і доцільність у межах загальнотеоретичного понятійного апарату, який стосується питань правової соціалізації, правосвідомості, правової культури особи, використання протилежних за змістом понять «правове виховання» і «правове антивиховання».The author has provided the initial elements of the justification of the possibility of using such contrary terminology as “legal education” and “legal anti-education” with the reference to the problem of significant impact on a person in the process of the legal socialization, not only positive, but also negative phenomena of legal reality.
It has been noted that legal education is one of the essential factors in the formation of the motivation of lawful behavior. In the narrow sense “legal education” is an activity aimed at achieving such desirable (expected) social outcomes as raising the level of legal awareness and legal culture of a person, social group, and society. In the broad sense, “legal education” is the influence of any phenomenon of the legal system of society on the legal awareness, legal culture of a person (people). At the same time, the notion of “legal system of society” covers only the system of phenomena that reflect the legal organization of society, that is, “negative” legal phenomena unlike “positive” one in the logic of things are not and can not be its elements. Legal anti-education involves the destructive effect of negative phenomena of legal reality (“legal life of society”) on the person’s legal awareness, which leads to its deformation, the development of mass legal nihilism and, accordingly, to lower the level of legal culture of society, since its precondition and mandatory element is “positive legal awareness” of citizens (its alternative – “nihilistic legal awareness”)
Specific heat of MgB_2 after irradiation
We studied the effect of disorder on the superconducting properties of
polycrystalline MgB_2 by specific-heat measurements. In the pristine state,
these measurements give a bulk confirmation of the presence of two
superconducting gaps with 2 Delta 0 / k_B T_c = 1.3 and 3.9 with nearly equal
weights. The scattering introduced by irradiation suppresses T_c and tends to
average the two gaps although less than predicted by theory. We also found that
by a suitable irradiation process by fast neutrons, a substantial bulk increase
of dH_{c2}/dT at T_c can be obtained without sacrificing more than a few
degrees in T_c. The upper critical field of the sample after irradiation
exceeds 28 T at T goes to 0 K.Comment: 11 pages text, 6 figures, accepted by Journal of Physics: Condensed
Matte
Super-Eddington accretion in the Q2237+0305 quasar?
The interband time lags between the flux variations of the Q2237+0305 quasar
have been determined from light curves in the Johnson-Cousins V, R, and I
spectral bands. The values of the time lags for filter pairs R-V, I-R, and I-V
are significantly higher than those predicted by the standard accretion disk
model by Shakura and Sunyaev. To explain the discrepancy, the idea of a
supercritical accretion regime in quasars considered in 1973 by Shakura and
Sunyaev is applied. This regime has been shown by them to cause an extended
scattering envelope around the accretion disk. The envelope efficiently
scatters and re-emits the radiation from the accretion disk and thus increases
the apparent disk size. We made use of analytical expressions for the envelope
radius and temperature derived by Shakura and Sunyaev in their analysis of
super-Eddington accretion and show that our results are consistent with the
existence of such an envelope. The corresponding parameters of the accretion
regime were calculated. They provide the radii of the envelope in the V, R, and
I spectral bands consistent with the inter-band time lags determined in our
work.Comment: 11 pages, 4 figure
On the Ginzburg-Landau Analysis of the Upper Critical Field Hc2 in MgB2
Temperature dependence of the upper critical field Hc2 (T) for the
superconducting magnesium diboride, MgB2, is studied in the vicinity of Tc by
using a two-band Ginzburg-Landau (G-L) theory. The temperature dependence of
Hc2 (T) near Tc exhibits a positive curvature. In addition, the calculated
temperature dependence and its higher order derivatives are also shown to be in
a good agreement with the experimental data. In analogy with the multi-band
character of Eliashberg microscopic theory, the positive curvature of Hc2 (T)
is described reasonably by solving the two-band of G-L theory.Comment: 14 pages, 2 figures, submitted to SUST November 200
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