850 research outputs found
Research of regional growth and development theories
Исследование теорий регионального экономического рост
Conductivity, weak ferromagnetism and charge instability in single crystal
The temperature dependence of resistivity, magnetization and electron-spin
resonance of the single crystal were measured in temperature
range of . Magnetization hysteresis in applied magnetic field
up to 0.7 T at , irreversible temperature behavior of
magnetization and resistivity were found . The obtained data were explained in
terms of degenerate tight binding model using random phase approximation. The
contribution of holes in and bands of manganese ions to the
conductivity, optical absorbtion spectra and charge instability in were studied. Charge susceptibility maxima resulted from the competition of
the on-site Coulomb interaction between the holes in different orbitals and
small hybridization of sub-bands were calculated at .Comment: 6 pages, 12 figure
Організація фізичного виховання школярів спеціальних медичних груп
Актуальність дослідження зумовлена невизначеністю системи організації фізичного виховання школярів спеціальних медичних груп. Завдання дослідження – узагальнити досвід теорії й практики з проблеми організації та методики проведення уроків фізичної культури з учнями спеціальних медичних груп. Найбільш ефек-тивний вплив на покращання здоров’я дітей можна здійснювати, проводячи заняття учнів спеціальної медичної групи на уроках фізичної культури, які проводяться окремою підгрупою за розкладом уроків основної медичної групи, та заняття учнів спеціальної медичної групи на уроках фізичної культури, що проводяться в позаурочний час. Отже, на сьогодні не розв’язаною залишається проблема організації уроків фізичної культури з учнями спеціальної медичної групи. Наявні підходи до проведення таких занять мають переваги та недоліки об’єктивного й суб’єктивного характеру. The research actuality is caused by the vagueness of the system of organization of physical education of schoolchildren in special medical groups. Research task: to generalize the experience of theory and practice of organization and methodology of conducting lesson of physical culture with students of special medical groups. The most effective influence on improvement of children health can made by organizing physical culture lessons for schoolchildren in special medical groups which are conducted to a separate group on the lessons curriculum of basic medical group and the lessons for students of the special medical groups which are organized in after-school time. It is consequently that nowadays a problem of organization of physical culture lessons with the students of. special medical groups stays unsolved Existent methods of organization of such lessons have advantages and disadvantages of objective and subjective character
Particle Acceleration and Magnetic Dissipation in Relativistic Current Sheet of Pair Plasmas
We study linear and nonlinear development of relativistic and
ultrarelativistic current sheets of pair plasmas with antiparallel magnetic
fields. Two types of two-dimensional problems are investigated by
particle-in-cell simulations. First, we present the development of relativistic
magnetic reconnection, whose outflow speed is an order of the light speed c. It
is demonstrated that particles are strongly accelerated in and around the
reconnection region, and that most of magnetic energy is converted into
"nonthermal" part of plasma kinetic energy. Second, we present another
two-dimensional problem of a current sheet in a cross-field plane. In this
case, the relativistic drift kink instability (RDKI) occurs. Particle
acceleration also takes place, but the RDKI fast dissipates the magnetic energy
into plasma heat. We discuss the mechanism of particle acceleration and the
theory of the RDKI in detail. It is important that properties of these two
processes are similar in the relativistic regime of T > mc^2, as long as we
consider the kinetics. Comparison of the two processes indicates that magnetic
dissipation by the RDKI is more favorable process in the relativistic current
sheet. Therefore the striped pulsar wind scenario should be reconsidered by the
RDKI.Comment: To appear in ApJ vol. 670; 60 pages, 27 figures; References and typos
are fixe
Winds, B-Fields, and Magnetotails of Pulsars
We investigate the emission of rotating magnetized neutron stars due to the
acceleration and radiation of particles in the relativistic wind and in the
magnetotail of the star. We consider that the charged particles are accelerated
by driven collisionless reconnection. Outside of the light cylinder, the star's
rotation acts to wind up the magnetic field to form a predominantly azimuthal,
slowly decreasing with distance, magnetic field of opposite polarity on either
side of the equatorial plane normal to the star's rotation axis. The magnetic
field annihilates across the equatorial plane with the magnetic energy going to
accelerate the charged particles to relativistic energies. For a typical
supersonically moving pulsar, the star's wind extends outward to the standoff
distance with the interstellar medium. At larger distances, the power output of
pulsar's wind of electromagnetic field and relativistic particles
is {\it redirected and collimated into the magnetotail} of the star. In the
magnetotail it is proposed that equipartition is reached between the magnetic
energy and the relativistic particle energy. For such conditions, synchrotron
radiation from the magnetotails may be a significant fraction of
for high velocity pulsars. An equation is derived for the radius of the
magnetotail as a function of distance from the star.
For large distances , of the order of the distance travelled by the
star, we argue that the magnetotail has a `trumpet' shape owing to the slowing
down of the magnetotail flow.Comment: 11 pages, 4 figures, accepted for publication in Ap
Strongly anisotropic magnetocaloric effect in a dipolar magnet LiGdF
We report the detailed study of the magnetocaloric effect (MCE) in a
dipolar-Heisenberg magnet LiGdF using magnetization measurements performed
on a single crystal sample. Entropy variation on isothermal demagnetization
from the magnetic field up to 3 T is determined in the temperature range 2-10 K
for two principal directions of the applied field (parallel and perpendicular
to the tetragonal -axis of the crystal). The MCE is found to be highly
anisotropic, with the cooling efficiency being up to twice higher at
. The results are nicely interpreted in the frame of a
conventional molecular field approach taking into account considerable
anisotropy of the paramagnetic Curie-Weiss temperature. These results are
compared to earlier studies of MCE in powder samples of LiGdF [T. Numazawa
et al., AIP Conf. Proc. 850, 1579 (2006)] as well as with analogous data for
other well known magnetocaloric materials. Our findings may open new
possibilities to enhance the efficiency of magnetic refrigeration in the liquid
helium-4 temperature range.Comment: 4 pages, 3 figure
Polymorphisms in genes involved in the absorption, distribution, metabolism, and excretion of drugs in the Kazakhs of Kazakhstan
A list of SNPs that were not found in heterozygous or homozygous variants. (DOC 83Â kb
Locking of the Rotation of Disk-Accreting Magnetized Stars
We investigate the rotational equilibrium state of a disk accreting
magnetized stars using axisymmetric magnetohydrodynamic (MHD) simulations. In
this ``locked'' state, the spin-up torque balances the spin-down torque so that
the net average torque on the star is zero. We investigated two types of
initial conditions, one with a relatively weak stellar magnetic field and a
high coronal density, and the other with a stronger stellar field and a lower
coronal density. We observed that for both initial conditions the rotation of
the star is locked to the rotation of the disk. In the second case, the radial
field lines carry significant angular momentum out of the star. However, this
did not appreciably change the condition for locking of the rotation of the
star. We find that in the equilibrium state the corotation radius is
related to the magnetospheric radius as for
case (1) and for case (2). We estimated periods of
rotation in the equilibrium state for classical T Tauri stars, dwarf novae and
X-ray millisecond pulsars.Comment: 10 pages, 9 figures. Accepted by ApJ, will appear in vol. 634, 2005
December
Microscopic spin Hamiltonian for a dipolar-Heisenberg magnet LiGdF4 from EPR measurements
Low-temperature electron paramagnetic resonance measurements are performed on
single crystals of LiY_{1-x}Gd_xF_4 with weak x=0.005 and moderate x=0.05
concentration of Gd ions. Modeling of the experimental spectra allows us to
precisely determine microscopic parameters of the spin Hamiltonian of the
parent LiGdF4 material, including the nearest-neighbor exchange constant. The
obtained parameters are further tested by comparing a strongly anisotropic
Curie-Weiss temperature obtained for LiGdF4 in our static magnetization
measurements with theoretically computed values. We find a fine balance between
principal magnetic interactions in LiGdF4, which results in a hidden magnetic
frustration presumably leading to a delayed magnetic ordering and an enhanced
magnetocaloric effect at low temperatures.Comment: 6 pages, 6 figure
Pollen quality and pollen productivity of blue honeysuckle species and varieties
Studies to assess the pollen quality and pollen productivity of blue honeysuckle were conducted on the ecosystem dendrological territory of the Siberian Botanical garden of TSU (Tomsk). Objects of research: 8 varieties and 4 species of blue honeysuckle – ‘Velvet’, ‘Berel’, ‘Vasyuganskaya’, ‘Zolushka’, ‘Lazurnaya’, ‘Ogneny Opal’, ‘Selena’, ‘Tomichka’, Lonicera altaica, L. edulis, L. kamtschatica, L. turczaninovii. It was found that the ‘Ogneny Opal’ and ‘Velvet’ varieties have low fertility, and the ‘Berel’ and L. edulis have an average fertility. Other varieties and species of honeysuckle have high pollen fertility. The viability of pollen with high values is more than 60 % – ‘Berel’, ‘Vasyuganskaya’, ‘Lazurnaya’, L. turczaninovii, L. kamtschatica, with average values from 40% to 60 % – ‘Selena’, ‘Tomichka’ and L. altaica, with low values – less than 40 % – ‘Velvet’, ‘Zolushka’, ‘Ogneny Opal’ and L. edulis. High pollen productivity – more than 20,000 pollen grains per flower – ‘Tomichka’, L. kamtschatica, L. turczaninovii and L. edulis, average productivity - from 10,000 to 20,000 pollen grains – ‘Berel’, ‘Vasyuganskaya’, ‘Zolushka’, ‘Lazurnaya’, ‘Selena’ and L. altaica, low productivity – less than 10,000 pollen grains per flower – ‘Velvet’, ‘Ogneny Opal’. It is recommended to use at least 10% of varieties with high pollen viability and pollen productivity as pollinators when creating industrial honeysuckle plantations: ‘Lazurnaya’, ‘Vasyuganskaya’, and ‘Berel’
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