29,797 research outputs found
Interplay between elastic fields due to gravity and a partial dislocation for a hard-sphere crystal coherently grown under gravity: driving force for defect disappearance
We previously observed that an intrinsic staking fault shrunk through a glide
of a Shockley partial dislocation terminating its lower end in a hard-sphere
crystal under gravity coherently grown in by Monte Carlo simulations
[Mori et al., Molec. Phys. 105, 1377 (2007)]; it was an answer to a one-decade
long standing question why the stacking disorder in colloidal crystals reduced
under gravity [Zhu et al., Nature 387, 883 (1997)]. Here, we present an elastic
energy calculation; in addition to the self-energy of the partial dislocation
[Mori et al., Prog. Theor. Phys. Suppl. 178, 33 (2009)] we calculate the
cross-coupling term between elastic field due to gravity and that due to a
Shockley partial dislocation. The cross term is a increasing function of the
linear dimension R over which the elastic field expands, showing that a driving
force arises for the partial dislocation moving toward the upper boundary of a
grain.Comment: 8pages, 4figures, to be published in Molecular Physic
The \gamma-ray production in neutral-current neutrino oxygen interaction in the energy range above 100 MeV
We calculate the cross section of the gamma-ray production from
neutral-current neutrino-oxygen quasi-elastic interaction, , or , in
which the residual nuclei (15N* or 15O*) lead to the gamma-ray emission with
gamma-ray energy >6 MeV at the branching ratio of 41%. Above 200 MeV, this
cross section dominates over that of gamma-ray production from the inelastic
reaction, . In the present calculation, spectral
function and the spectroscopic factors of
states are essential. The gamma-ray production is dominated by the deexcitation
of state of the residual nucleus
The Grothendieck Group of a Quantum Projective Space Bundle
We compute the Grothendieck group K_0 of non-commutative analogues of quantum
projective space bundles. Our results specialize to give the Grothendieck
groups of non-commutative analogues of projective spaces, and specialize to
recover the Grothendieck group of a usual projective space bundle over a
regular noetherian separated scheme. As an application we develop an
intersection theory for the quantum ruled surfaces defined by Van den Bergh.Comment: This paper is being replaced so I can correct the metadata, the
title! I (Paul) spelled Grothendieck's name incorrectly. The paper is being
reposted with the journal reference and doi added to the metadat
Anomalous infrared spectra of hybridized phonons in type-I clathrate BaGaGe
The optical conductivity spectra of the rattling phonons in the clathrate
BaGaGe are investigated in detail by use of the terahertz
time-domain spectroscopy. The experiment has revealed that the lowest-lying
vibrational mode of a Ba(2) ion consists of a sharp Lorentzian peak at
1.2 THz superimposed on a broad tail weighted in the lower frequency regime
around 1.0 THz. With decreasing temperature, an unexpected linewidth broadening
of the phonon peak is observed, together with monotonic softening of the phonon
peak and the enhancement of the tail structure. These observed anomalies are
discussed in terms of impurity scattering effects on the hybridized phonon
system of rattling and acoustic phonons.Comment: Submitted to JPS
Silicon nitride powder
The characteristics and preparation methods of Si3N4 are reviewed. Special emphasis is placed on the correlation between impurities and strength of sintered Si3N4
Baryon loading and the Weibel instability in gamma-ray bursts
The dynamics of two counter-streaming electron-positron-ion unmagnetized
plasma shells with zero net charge is analyzed in the context of magnetic field
generation in GRB internal shocks due to the Weibel instability. The effects of
large thermal motion of plasma particles, arbitrary mixture of plasma species
and space charge effects are taken into account. We show that, although thermal
effects slow down the instability, baryon loading leads to a non-negligible
growth rate even for large temperatures and different shell velocities, thus
guaranteeing the robustness and the occurrence of the Weibel instability for a
wide range of scenarios.Comment: 6 pages, 4 figures. Accepted for publication in MNRA
Coexistence of superconductivity and antiferromagnetism in self-doped bilayer t-t'-J model
A self-doped bilayer t-t'-J model of an electron- and a hole-doped planes is
studied by the slave-boson mean-field theory. A hopping integral between the
differently doped planes, which are generated by a site potential, are
renormalized by the electron-electron correlation. We find coexistent phases of
antiferromagnetic (AFM) and superconducting orders, although the magnitudes of
order parameters become more dissimilar in the bilayer away from half-filling.
Fermi surfaces (FS's) with the AFM order show two pockets around the nodal and
the anti-nodal regions. These results look like a composite of electron- and
hole-doped FS's. In the nodal direction, the FS splitting is absent even in the
bilayer system, since one band is flat due to the AFM order.Comment: 6 pages, 4 figure
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