331 research outputs found
Spin orientation by electric current in (110) quantum wells
We develop a theory of spin orientation by electric current in (110)-grown
semiconductor quantum wells. The controversy in the factor of two from two
existed approaches is resolved by pointing out the importance of energy
relaxation in this problem. The limiting cases of fast and slow energy
relaxation relative to spin relaxation are considered for asymmetric (110)
quantum wells. For symmetricly-doped structures the effect of spin orientation
is shown to exist due to spatial fluctuations of the Rashba spin-orbit
splitting. We demonstrate that the spin orientation depends strongly on the
correlation length of these fluctuations as well as on the ratio of the energy
and spin relaxation rates. The time-resolved kinetics of spin polarization by
electric current is also governed by the correlation length being not purely
exponential at slow energy relaxation. Electrical spin orientation in
two-dimensional topological insulators is calculated and compared with the spin
polarization induced by the magnetic field.Comment: 8 pages, 2 figure
Rational solutions of the discrete time Toda lattice and the alternate discrete Painleve II equation
The Yablonskii-Vorob'ev polynomials , which are defined by a second
order bilinear differential-difference equation, provide rational solutions of
the Toda lattice. They are also polynomial tau-functions for the rational
solutions of the second Painlev\'{e} equation (). Here we define
two-variable polynomials on a lattice with spacing , by
considering rational solutions of the discrete time Toda lattice as introduced
by Suris. These polynomials are shown to have many properties that are
analogous to those of the Yablonskii-Vorob'ev polynomials, to which they reduce
when . They also provide rational solutions for a particular
discretisation of , namely the so called {\it alternate discrete}
, and this connection leads to an expression in terms of the Umemura
polynomials for the third Painlev\'{e} equation (). It is shown that
B\"{a}cklund transformation for the alternate discrete Painlev\'{e} equation is
a symplectic map, and the shift in time is also symplectic. Finally we present
a Lax pair for the alternate discrete , which recovers Jimbo and Miwa's
Lax pair for in the continuum limit .Comment: 23 pages, IOP style. Title changed, and connection with Umemura
polynomials adde
The Hamiltonian Structure of the Second Painleve Hierarchy
In this paper we study the Hamiltonian structure of the second Painleve
hierarchy, an infinite sequence of nonlinear ordinary differential equations
containing PII as its simplest equation. The n-th element of the hierarchy is a
non linear ODE of order 2n in the independent variable depending on n
parameters denoted by and . We introduce new
canonical coordinates and obtain Hamiltonians for the and
evolutions. We give explicit formulae for these Hamiltonians showing that they
are polynomials in our canonical coordinates
Magneto-gyrotropic effects in semiconductor quantum wells (review)
Magneto-gyrotropic photogalvanic effects in quantum wells are reviewed. We
discuss experimental data, results of phenomenological analysis and microscopic
models of these effects. The current flow is driven by spin-dependent
scattering in low-dimensional structures gyrotropic media resulted in asymmetry
of photoexcitation and relaxation processes. Several applications of the
effects are also considered.Comment: 28 pages, 13 figure
Geoantineutrino Spectrum, 3He/4He-ratio Distribution in the Earth's Interior and Slow Nuclear Burning on the Boundary of the Liquid and Solid Phases of the Earth's Core
The description problem of geoantineutrino spectrum and reactor antineutrino
experimental spectrum in KamLAND, which takes place for antineutrino energy
\~2.8 MeV, and also the experimental results of the interaction of uranium
dioxide and carbide with iron-nickel and silicaalumina melts at high pressure
(5-10 GP?) and temperature (1600-2200C) have motivated us to consider the
possible consequences of the assumption made by V.Anisichkin and coauthors that
there is an actinid shell on boundary of liquid and solid phases of the Earth's
core. We have shown that the activation of a natural nuclear reactor operating
as the solitary waves of nuclear burning in 238U- and/or 232Th-medium (in
particular, the neutron- fission progressive wave of Feoktistov and/or
Teller-Ishikawa-Wood) can be such a physical consequence. The simplified model
of the kinetics of accumulation and burnup in U-Pu fuel cycle of Feoktistov is
developed. The results of the numerical simulation of neutron-fission wave in
two-phase UO2/Fe medium on a surface of the Earth's solid core are presented.
The georeactor model of 3He origin and the 3He/4He-ratio distribution in the
Earth's interior is offered. It is shown that the 3He/4He ratio distribution
can be the natural quantitative criterion of georeactor thermal power. On the
basis of O'Nions-Evensen-Hamilton geochemical model of mantle differentiation
and the crust growth supplied by actinid shell on the boundary of liquid and
solid phases of the Earth's core as a nuclear energy source (georeactor with
power of 30 TW), the tentative estimation of geoantineutrino intensity and
geoantineutrino spectrum on the Earth surface are given.Comment: 28 pages, 12 figures. Added text, formulas, figures and references.
Corrected equations. Changed content of some section
Non-invasive comprehensive laboratory and ultrasound method for the evaluation of the functional status of the liver in patients with type 2 diabetes mellitus
The article analyzes the methods of assessment of fatty infiltration of the liver in patients with type 2 diabetes and a new non-invasive method using laboratory, echohepatodensitographic and tomographic study options. Discriminant models are developed which are used as variables in the values activity of aspartate aminotransferase, gamma-glutamiltranspeptidase, coefficient of density of the tissue in the anterior surface of the liver in echohepatodensitographic study, the density of the liver in tomographic ones study. Using the model, you can define the degree of steatoinfiltration of the liver from minimal to marked. The greatest impact of the classification in the model had the density of the liver determined by tomographic ones and echohepatodensitographicstudy.Π ΡΡΠ°ΡΡΠ΅ ΠΏΡΠΎΠ°Π½Π°Π»ΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Ρ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΎΡΠ΅Π½ΠΊΠΈ ΠΆΠΈΡΠΎΠ²ΠΎΠΉ ΠΈΠ½ΡΠΈΠ»ΡΡΡΠ°ΡΠΈΠΈ ΠΏΠ΅ΡΠ΅Π½ΠΈ Ρ Π±ΠΎΠ»ΡΠ½ΡΡ
ΡΠ°Ρ
Π°ΡΠ½ΡΠΌ Π΄ΠΈΠ°Π±Π΅ΡΠΎΠΌ 2 ΡΠΈΠΏΠ° ΠΈ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ Π½ΠΎΠ²ΡΠΉ Π½Π΅ΠΈΠ½Π²Π°Π·ΠΈΠ²Π½ΡΠΉ ΠΌΠ΅ΡΠΎΠ΄ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ Π»Π°Π±ΠΎΡΠ°ΡΠΎΡΠ½ΡΡ
, ΡΡ
ΠΎΠ³Π΅ΠΏΠ°ΡΠΎΠ΄Π΅Π½ΡΠΈΡΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈ ΡΠΎΠΌΠΎΠ³ΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ. Π Π°Π·ΡΠ°Π±ΠΎΡΠ°Π½Ρ Π΄ΠΈΡΠΊΡΠΈΠΌΠΈΠ½Π°Π½ΡΠ½ΡΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈ, Π³Π΄Π΅ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΡ
ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΡΡΡΡ Π²Π΅Π»ΠΈΡΠΈΠ½Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ Π°ΡΠΏΠ°ΡΡΠ°ΡΠ°ΠΌΠΈΠ½ΠΎΡΡΠ°Π½ΡΡΠ΅ΡΠ°Π·Ρ, Π³Π°ΠΌΠΌΠ°-Π³Π»ΡΡΠ°ΠΌΠΈΠ»ΡΡΠ°Π½ΡΠΏΠ΅ΠΏΡΠΈΠ΄Π°Π·Ρ, ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΠΈ ΡΠΊΠ°Π½ΠΈ Π² ΠΎΠ±Π»Π°ΡΡΠΈ ΠΏΠ΅ΡΠ΅Π΄Π½Π΅ΠΉ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΏΠ΅ΡΠ΅Π½ΠΈ ΠΏΡΠΈ ΡΡ
ΠΎΠ³Π΅ΠΏΠ°ΡΠΎΠ΄Π΅Π½ΡΠΈΡΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΈ,ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΠΈ ΠΏΠ΅ΡΠ΅Π½ΠΈ ΠΏΡΠΈ ΡΠΎΠΌΠΎΠ³ΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΈ. ΠΡΠΏΠΎΠ»ΡΠ·ΡΡ ΠΌΠΎΠ΄Π΅Π»ΠΈ, ΠΌΠΎΠΆΠ½ΠΎ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΠΈΡΡ ΡΡΠ΅ΠΏΠ΅Π½Ρ ΠΆΠΈΡΠΎΠ²ΠΎΠΉ ΠΈΠ½ΡΠΈΠ»ΡΡΡΠ°ΡΠΈΠΈ ΠΏΠ΅ΡΠ΅Π½ΠΈ ΠΎΡ ΠΌΠΈΠ½ΠΈΠΌΠ°Π»ΡΠ½ΠΎΠΉ Π΄ΠΎ Π²ΡΡΠ°ΠΆΠ΅Π½Π½ΠΎΠΉ. ΠΠ°ΠΈΠ±ΠΎΠ»ΡΡΠ΅Π΅ ΠΊΠ»Π°ΡΡΠΈΡΠΈΠΊΠ°ΡΠΈΠΎΠ½Π½ΠΎΠ΅ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π² ΠΌΠΎΠ΄Π΅Π»ΠΈ ΠΈΠΌΠ΅Π»Π° Π²Π΅Π»ΠΈΡΠΈΠ½Π° ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΠΈ ΠΏΠ΅ΡΠ΅Π½ΠΈ, ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ΅ΠΌΠ°Ρ ΠΏΡΠΈ ΡΠΎΠΌΠΎΠ³ΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΌ ΠΈ Π·Ρ
ΠΎΠ΄Π΅Π½ΡΠΈΡΠΎΠ³ΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΈ
Gravitational Couplings of Intrinsic Spin
The gravitational couplings of intrinsic spin are briefly reviewed. A
consequence of the Dirac equation in the exterior gravitational field of a
rotating mass is considered in detail, namely, the difference in the energy of
a spin-1/2 particle polarized vertically up and down near the surface of a
rotating body is . Here is the latitude and
, where and are, respectively, the angular
momentum and radius of the body. It seems that this relativistic quantum
gravitational effect could be measurable in the foreseeable future.Comment: LaTeX file, no figures, 16 page
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