975 research outputs found
Orbital order and ferrimagnetic properties of the new compound
By means of the LSDA+U method and the Green function method, we investigate
the electronic and magnetic properties of the new material of
SrCaReCuO. Our LSDA+U calculation shows that this system is
an insulator with a net magnetic moment of 1.01 /f.u., which is in
good agreement with the experiment. Magnetic moments are mainly located at Cu
atoms, and the magnetic moments of neighboring Cu sites align anti-parallel. It
is the non-magnetic Re atoms that induce an orbital order of electrons of
Cu atoms, which is responsible for the strong exchange interaction and the high
magnetic transition temperature. Based on the LSDA+U results, we introduce an
effective model for the spin degrees of freedom, and investigate the
finite-temperature properties by the Green function method. The obtained
results are consistent with the experimental results, indicating that the
spin-alternating Heisenberg model is suitable for this compound.Comment: 8 pages and 5 figur
A central extension of \cD Y_{\hbar}(\gtgl_2) and its vertex representations
A central extension of \cD Y_{\hbar}(\gtgl_2) is proposed. The bosonization
of level module and vertex operators are also given.Comment: 10 pages, AmsLatex, to appear in Lett. in Math. Phy
PLACE OF LOW-MOLECULAR-WEIGHT HEPARINS IN INTENSIVE THERAPY OF HEPATIC INSUFFICIENCY
The practical significance of heparin low-molecular fractions as inhibitors of inflammation and antithrombin III consumption reduction were studied. That is most critical in acute hepatic failure. The study was performed using the low-molecular-weight heparin (Nadroparin calcium) in low (prophylactic) doses of 2000 anti-factor Xa units daily per 1 meter squared in the form of continuous intravenous infusion. The cohort study proved the nadroparin positive effect on carbohydrate and protein metabolism in children with acute poisoning by hepatotoxic poisons, The significant decrease in the quantitative assessment of disseminated intravascular coagulation relative to the comparison group has been revealed, and the decrease in 28-day mortality from 42 to 13 % has been found in children receiving nadroparin. Conclusions are drawn on the feasibility of introducing low molecular weight heparins into the intensive care regimen of liver failure
Fusion products, Kostka polynomials, and fermionic characters of su(r+1)_k
Using a form factor approach, we define and compute the character of the
fusion product of rectangular representations of \hat{su}(r+1). This character
decomposes into a sum of characters of irreducible representations, but with
q-dependent coefficients. We identify these coefficients as (generalized)
Kostka polynomials. Using this result, we obtain a formula for the characters
of arbitrary integrable highest-weight representations of \hat{su}(r+1) in
terms of the fermionic characters of the rectangular highest weight
representations.Comment: 21 pages; minor changes, typos correcte
Permanent current from non-commutative spin algebra
We show that a spontaneous electric current is induced in a nano-scale
conducting ring just by putting three ferromagnets. The current is a direct
consequence of the non-commutativity of the spin algebra, and is proportional
to the non-coplanarity (chirality) of the magnetization vectors. The
spontaneous current gives a natural explanation to the chirality-driven
anomalous Hall effect.Comment: 7 pages, 4 figures on separate pag
On Bohr-Sommerfeld bases
This paper combines algebraic and Lagrangian geometry to construct a special
basis in every space of conformal blocks, the Bohr-Sommerfeld (BS) basis. We
use the method of [D. Borthwick, T. Paul and A. Uribe, Legendrian distributions
with applications to the non-vanishing of Poincar\'e series of large weight,
Invent. math, 122 (1995), 359-402, preprint hep-th/9406036], whereby every
vector of a BS basis is defined by some half-weighted Legendrian distribution
coming from a Bohr-Sommerfeld fibre of a real polarization of the underlying
symplectic manifold. The advantage of BS bases (compared to bases of theta
functions in [A. Tyurin, Quantization and ``theta functions'', Jussieu preprint
216 (Apr 1999), e-print math.AG/9904046, 32pp.]) is that we can use information
from the skillful analysis of the asymptotics of quantum states. This gives
that Bohr-Sommerfeld bases are unitary quasi-classically. Thus we can apply
these bases to compare the Hitchin connection with the KZ connection defined by
the monodromy of the Knizhnik-Zamolodchikov equation in combinatorial theory
(see, for example, [T. Kohno, Topological invariants for 3-manifolds using
representations of mapping class group I, Topology 31 (1992), 203-230; II,
Contemp. math 175} (1994), 193-217]).Comment: 43 pages, uses: latex2e with amsmath,amsfonts,theore
Coherent long-range transfer of angular momentum between magnon Kittel modes by phonons
We report ferromagnetic resonance in the normal configuration of an
electrically insulating magnetic bilayer consisting of two yttrium iron garnet
(YIG) films epitaxially grown on both sides of a 0.5-mm-thick nonmagnetic
gadolinium gallium garnet (GGG) slab. An interference pattern is observed and
it is explained as the strong coupling of the magnetization dynamics of the two
YIG layers either in phase or out of phase by the standing transverse sound
waves, which are excited through a magnetoelastic interaction. This coherent
mediation of angular momentum by circularly polarized phonons through a
nonmagnetic material over macroscopic distances can be useful for future
information technologies
First Detection of 12CO (1--0) Emission from Two Narrow-Line Seyfert 1 Galaxies
In order to investigate how the growth of galactic bulges progresses with the
growth of central black holes (BHs), we observed molecular gas (fuel for the
coming star formation) in possibly young active galaxies, narrow-line Seyfert 1
galaxies (NLS1s). We present the results of radio observations of 12CO(1--0)
using the Nobeyama Millimeter Array (with 2--4 kpc spatial resolution) for two
FIR-bright NLS1s, yielding the first detection of their CO emission.
Corresponding molecular--gas masses M(H2) of (1-3) X 109 Msun are the 2nd and
4th largest ones among NLS1s. By estimating dynamical masses and bulge masses
M(bulge) for these two NLS1s using CO channel map and CO line widths, we found
M(H2) amount to 0.13--0.35 of these masses. Taking account the star formation
efficiency (~ 0.1), the increase in M(bulge) in those NLS1s in the near future
(~< 10^{7.5} yr) is expected not to be a huge fraction (1--5% of the
preexisting stars). Bulge growth may have finished before BH growth, or
bulge--BH coevolution may proceed with many, occasional discrete events, where
one coevolution event produces only a small amount of mass growth of BHs and of
bulges. We also discuss the ratios of star-formation rate--to--gas accretion
rate onto BHs, finding that two NLS1s have very small ratios (~ 1) compared
with the M(bulge)/M(BH) ratios found in active and inactive galaxies (~ 700).
This huge difference suggests either the non-overlapped coevolution, long star
formation duration or temporarily high accretion rate during NLS1 phase.Comment: 29 pages, 8 figures, Accepted for publication in The Astrophysical
Journa
Localization of N=4 Superconformal Field Theory on S^1 x S^3 and Index
We provide the geometrical meaning of the superconformal index.
With this interpretation, the superconformal index can be realized
as the partition function on a Scherk-Schwarz deformed background. We apply the
localization method in TQFT to compute the deformed partition function since
the deformed action can be written as a -exact form. The
critical points of the deformed action turn out to be the space of flat
connections which are, in fact, zero modes of the gauge field. The one-loop
evaluation over the space of flat connections reduces to the matrix integral by
which the superconformal index is expressed.Comment: 42+1 pages, 2 figures, JHEP style: v1.2.3 minor corrections, v4 major
revision, conclusions essentially unchanged, v5 published versio
Stochastic series expansion method with operator-loop update
A cluster update (the ``operator-loop'') is developed within the framework of
a numerically exact quantum Monte Carlo method based on the power series
expansion of exp(-BH) (stochastic series expansion). The method is generally
applicable to a wide class of lattice Hamiltonians for which the expansion is
positive definite. For some important models the operator-loop algorithm is
more efficient than loop updates previously developed for ``worldline''
simulations. The method is here tested on a two-dimensional anisotropic
Heisenberg antiferromagnet in a magnetic field.Comment: 5 pages, 4 figure
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