1,918 research outputs found
Interaction effects in assembly of magnetic nanoparticles
A specific absorption rate of a dilute assembly of various random clusters of
iron oxide nanoparticles in alternating magnetic field has been calculated
using Landau- Lifshitz stochastic equation. This approach simultaneously takes
into account both the presence of thermal fluctuations of the nanoparticle
magnetic moments, and magneto-dipole interaction between the nanoparticles of
the clusters. It is shown that for usual 3D clusters the intensity of magneto-
dipole interaction is determined mainly by the cluster packing density eta =
Np*V/Vcl, where Np is the average number of the particles in the cluster, V is
the nanoparticle volume, and Vcl is the cluster volume. The area of the low
frequency hysteresis loop and the assembly specific absorption rate have been
found to be considerably reduced when the packing density of the clusters
increases in the range of 0.005 < eta < 0.4. The dependence of the specific
absorption rate on the mean nanoparticle diameter is retained with increase of
eta, but becomes less pronounced. For fractal clusters of nanoparticles, which
arise in biological media, in addition to considerable reduction of the
absorption rate, the absorption maximum is shifted to smaller particle
diameters. It is found also that the specific absorption rate of fractal
clusters increases appreciably with increase of the thickness of nonmagnetic
shells at the nanoparticle surfaces.Comment: The paper is accepted for Nanoscale Res. Let
Bethe subalgebras in affine Birman--Murakami--Wenzl algebras and flat connections for q-KZ equations
Commutative sets of Jucys-Murphyelements for affine braid groups of
types were defined. Construction of
-matrix representations of the affine braid group of type and its
distinguish commutative subgroup generated by the -type Jucys--Murphy
elements are given. We describe a general method to produce flat connections
for the two-boundary quantum Knizhnik-Zamolodchikov equations as necessary
conditions for Sklyanin's type transfer matrix associated with the two-boundary
multicomponent Zamolodchikov algebra to be invariant under the action of the
-type Jucys--Murphy elements. We specify our general construction to
the case of the Birman--Murakami--Wenzl algebras. As an application we suggest
a baxterization of the Dunkl--Cherednik elements in the double affine
Hecke algebra of type
Fractional Systems and Fractional Bogoliubov Hierarchy Equations
We consider the fractional generalizations of the phase volume, volume
element and Poisson brackets. These generalizations lead us to the fractional
analog of the phase space. We consider systems on this fractional phase space
and fractional analogs of the Hamilton equations. The fractional generalization
of the average value is suggested. The fractional analogs of the Bogoliubov
hierarchy equations are derived from the fractional Liouville equation. We
define the fractional reduced distribution functions. The fractional analog of
the Vlasov equation and the Debye radius are considered.Comment: 12 page
Off-shell two loop QCD vertices
We calculate the triple gluon, ghost-gluon and quark-gluon vertex functions
at two loops in the MSbar scheme in the chiral limit for an arbitrary linear
covariant gauge when the external legs are all off-shell.Comment: 29 latex pages, 32 figures, anc directory contains txt file with
electronic version of vertex functions for each of the three 3-point cases in
the MSbar scheme and includes the projection matrice
pair production in relativistic ions collision and its correspondence to electron-ion scattering
It is shown that the amplitudes of electron-ion scattering and pair
production in the Coulomb field of two colliding ions are sxpressed in the
terms of electron scattering amplitudes in the fields of the individual ions
via the Watson expansion. We have obtained the compact expressions for these
amplitudes valid in the high energy limit and discuss the crossing symmetry
relations among the considered processes.Comment: 5 pages, no figures, LaTEX; submitted to Physics Letters
Fractional Variations for Dynamical Systems: Hamilton and Lagrange Approaches
Fractional generalization of an exterior derivative for calculus of
variations is defined. The Hamilton and Lagrange approaches are considered.
Fractional Hamilton and Euler-Lagrange equations are derived. Fractional
equations of motion are obtained by fractional variation of Lagrangian and
Hamiltonian that have only integer derivatives.Comment: 21 pages, LaTe
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