1,762 research outputs found
CO(J=6-5) Observations of the Quasar SDSS1044-0125 at z = 5.8
We present a result of the quasar CO(J=6-5) observations of SDSSp
J104433.04-012502.2 at z = 5.8. Ten-days observations with the Nobeyama
Millimeter Array yielded an rms noise level of ~ 2.1 mJy/beam in a frequency
range from 101.28 GHz to 101.99 GHz at a velocity resolution of 120 km/s. No
significant clear emission line was detected in the observed field and
frequency range. Three sigma upper limit on the CO(J=6-5) luminosity of the
object is 2.8 x 10^10 K km/s pc^2, corresponding to a molecular gas mass of 1.2
x 10^11 Solar Mass, if a conversion factor of 4.5 Solar Mass /(K km/s pc^2) is
adopted. The obtained upper limit on CO luminosity is slightly smaller than
those observed in quasars at z=4-5 toward which CO emissions are detected.Comment: 4 pages, 3 figures, LaTeX2e, to appear in Publication of Astronomical
Society of Japan (PASJ), Postscript file available at
ftp://ftp.kusastro.kyoto-u.ac.jp/pub/iwata/preprint/sdss1044/sdss.ps.g
Nuclear incompressibility in the quasilocal density functional theory
We explore the ability of the recently established quasilocal density
functional theory for describing the isoscalar giant monopole resonance. Within
this theory we use the scaling approach and perform constrained calculations
for obtaining the cubic and inverse energy weighted moments (sum rules) of the
RPA strength. The meaning of the sum rule approach in this case is discussed.
Numerical calculations are carried out using Gogny forces and an excellent
agreement is found with HF + RPA results previously reported in literature. The
nuclear matter compression modulus predicted in our model lies in the range
210-230 MeV which agrees with earlier findings. The information provided by the
sum rule approach in the case of nuclei near the neutron drip line is also
discussed.Comment: 10 pages, LaTe
Homology of iterated semidirect products of free groups
Let be a group which admits the structure of an iterated semidirect
product of finitely generated free groups. We construct a finite, free
resolution of the integers over the group ring of . This resolution is used
to define representations of groups which act compatibly on , generalizing
classical constructions of Magnus, Burau, and Gassner. Our construction also
yields algorithms for computing the homology of the Milnor fiber of a
fiber-type hyperplane arrangement, and more generally, the homology of the
complement of such an arrangement with coefficients in an arbitrary local
system.Comment: 31 pages. AMSTeX v 2.1 preprint styl
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
Effects of Randomness on the Field-Induced Phase Transition in the S=1 Bond-Alternating Spin Chain NTENP
We report novel effects of randomness in the S=1 bond-alternating
antiferromagnetic chain compound with a dimer-singlet ground state
[Ni(N,N'-bis(3-aminopropyl)propane-1,3-diamine(mu-NO2]ClO4 abbreviated as
NTENP. The 15N NMR spectra develop a continuum with sharply peaked edges at low
temperatures, indicating an inhomogeneous staggered magnetization induced by
magnetic field. We attribute this to random anisotropic interactions due to
disorder of NO2 groups in the chains. The field-induced antiferromagnetic
transition exhibits remarkably anisotropic behavior. We propose that a
field-induced incoherent magnetization is transformed into a coherent
antiferromagnetic moment with spatially fluctuating amplitude.Comment: 4pages, 5 figues, submitted to J. Phys. Soc. Jp
Theory of Current-Driven Domain Wall Motion: A Poorman's Approach
A self-contained theory of the domain wall dynamics in ferromagnets under
finite electric current is presented.
The current is shown to have two effects; one is momentum transfer, which is
proportional to the charge current and wall resistivity (\rhow), and the
other is spin transfer, proportional to spin current.
For thick walls, as in metallic wires, the latter dominates and the threshold
current for wall motion is determined by the hard-axis magnetic anisotropy,
except for the case of very strong pinning.
For thin walls, as in nanocontacts and magnetic semiconductors, the
momentum-transfer effect dominates, and the threshold current is proportional
to \Vz/\rhow, \Vz being the pinning potential
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
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