2,068 research outputs found
Non-axial Octupole Deformations of N=Z Nuclei in Mass Region
By performing a fully three dimensional Hartree-Fock calculation with use of
the Skyrm forces, we demonstrate possibility of exotic deformations violating
both the reflection and the axial symmetries of N=Z nuclei in
mass region. The \Ytwo tetrahedral shape predicted in excited \Zr arises from a
shell gap at which is enhanced for the tetrahedron deformation.
Softness toward the \Ythree triangular deformation of the oblate state in \Se
is also predicted.Comment: 10 page
Mott Gap Excitations and Resonant Inelastic X-Ray Scattering in Doped Cuprates
Predictions are made for the momentum- and carrier-dependent degradation of
the Mott gap upon doping in high-Tc cuprates as would be observed in Cu K-edge
resonant inelastic x-ray scattering (RIXS). The two-dimensional Hubbard model
with second- and third-nearest-neighbor hopping terms has been studied by
numerical exact diagonalization. Special emphasis is placed on the
particle-hole asymmetry of the Mott gap excitations. We argue that the Mott gap
excitations observed by RIXS are significantly influenced by the interaction
between charge carriers and antiferromagnetic correlations.Comment: 4 pages, 4 figures, revised version; to be published in Phys. Rev.
Let
Raised polyamines in erythrocytes from melanoma-bearing mice and patients with solid tumours
The levels of polyamines (putrescine, spermidine and spermine) in erythrocytes and plasma were studied using Cloudman S-91 melanoma grown in the lungs of DBA/2 mice. Polyamine levels and the numbers of tumour-cell colonies in the lungs were determined at weekly intervals. Putrescine levels in both erythrocytes and plasma significantly increased 1 week after tumour inoculation. Three weeks after inoculation, however, putrescine levels in the erythrocytes showed a greater increase than those in plasma. Spermidine and spermine levels were initially high at 2 weeks in plasma and at 4 weeks in erythrocytes. However, by 6 weeks the spermidine levels showed a greater increase in erythrocytes than in plasma. These data suggest that erythrocytes may absorb and store polyamines released into the circulation
Tidal effects on magnetic gyration of a charged particle in Fermi coordinates
We examine the gyration motion of a charged particle, viewed from a reference
observer falling along the Z axis into a Schwarzschild black hole. It is
assumed that the magnetic field is constant and uniform along the Z axis, and
that the particle has a circular orbit in the X-Y plane far from the
gravitational source. When the particle as well as the reference observer
approaches the black hole, its orbit is disrupted by the tidal force. The final
plunging velocity increases in the non-relativistic case, but decreases if the
initial circular velocity exceeds a critical value, which is approximately
0.7c. This toy model suggests that disruption of a rapidly rotating star due to
a velocity-dependent tidal force may be quite different from that of a
non-relativistic star. The model also suggested that collapse of the orbit
after the disruption is slow in general, so that the particle subsequently
escapes outside the valid Fermi coordinates.Comment: 10 pages, 12 figure
A quasi-radial stability criterion for rotating relativistic stars
The stability properties of relativistic stars against gravitational collapse to black hole is a classical problem in general relativity. A sufficient criterion for secular instability was established by Friedman, Ipser and Sorkin (1988), who proved that a sequence of uniformly rotating barotropic stars is secularly unstable on one side of a turning point and then argued that a stronger result should hold: that the sequence should be stable on the opposite side, with the turning point marking the onset of secular instability. We show here that this expectation is not met. By computing in full general relativity the -mode frequency for a large number of rotating stars, we show that the neutral-stability point, i.e., where the frequency becomes zero, differs from the turning point for rotating stars. Using numerical simulations we validate that the new criterion can be used to assess the dynamical stability of relativistic rotating stars
Interaction and Localization of One-electron Orbitals in an Organic Molecule: Fictitious Parameter Analysis for Multi-physics Simulations
We present a new methodology to analyze complicated multi-physics simulations
by introducing a fictitious parameter. Using the method, we study quantum
mechanical aspects of an organic molecule in water. The simulation is
variationally constructed from the ab initio molecular orbital method and the
classical statistical mechanics with the fictitious parameter representing the
coupling strength between solute and solvent. We obtain a number of
one-electron orbital energies of the solute molecule derived from the
Hartree-Fock approximation, and eigenvalue-statistical analysis developed in
the study of nonintegrable systems is applied to them. Based on the results, we
analyze localization properties of the electronic wavefunctions under the
influence of the solvent.Comment: 4 pages, 5 figures, the revised version will appear in J. Phys. Soc.
Jpn. Vol.76 (No.1
Self-consistent study of topological superconductivity in two-dimensional quasicrystals
We study two-dimensional -wave topological superconductivity with Rashba
spin-orbit coupling and Zeeman field in Penrose and Ammann-Beenker
quasicrystals. By solving the Bogoliubov-de Gennes equations self-consistently
for not only the superconducting order parameter, but also the spin-dependent
Hartree potential, we show the stable occurrence of TSC with broken
time-reversal symmetry in both Penrose and Ammann-Beenker quasicrystals. The
topological nature of the quasicrystalline system is signified by the Bott
index . Topological phase transitions are found to occur, where changes
between 0 and , as the chemical potential or Zeeman field is varied. In
terms of self-consistent solutions, we demonstrate the existence of a Majorana
zero mode per edge or vortex when , consistently with the
bulk-edge/defect correspondence for periodic systems.Comment: 11 pages, 10 figure
Longitudinal magnetic excitation in KCuCl3 studied by Raman scattering under hydrostatic pressures
We measure Raman scattering in an interacting spin-dimer system KCuCl3 under
hydrostatic pressures up to 5 GPa mediated by He gas. In the pressure-induced
quantum phase, we observe a one-magnon Raman peak, which originates from the
longitudinal magnetic excitationand is observable through the second-order
exchange interaction Raman process. We report the pressure dependence of the
frequency, halfwidth and Raman intensity of this mode.Comment: 4 pages, 3 figures, inpress in JPCS as a proceeding of LT2
Discovery of a Wide Substellar Companion to a Nearby Low-Mass Star
We report the discovery of a wide (135+/-25 AU), unusually blue L5 companion
2MASS J17114559+4028578 to the nearby M4.5 dwarf G 203-50 as a result of a
targeted search for common proper motion pairs in the Sloan Digital Sky Survey
and the Two Micron All Sky Survey. Adaptive Optics imaging with Subaru
indicates that neither component is a nearly equal mass binary with separation
> 0.18", and places limits on the existence of additional faint companions. An
examination of TiO and CaH features in the primary's spectrum is consistent
with solar metallicity and provides no evidence that G 203-50 is metal poor. We
estimate an age for the primary of 1-5 Gyr based on activity. Assuming
coevality of the companion, its age, gravity and metallicity can be constrained
from properties of the primary, making it a suitable benchmark object for the
calibration of evolutionary models and for determining the atmospheric
properties of peculiar blue L dwarfs. The low total mass (M_tot=0.21+/-0.03
M_sun), intermediate mass ratio (q=0.45+/-0.14), and wide separation of this
system demonstrate that the star formation process is capable of forming wide,
weakly bound binary systems with low mass and BD components. Based on the
sensitivity of our search we find that no more than 2.2% of early-to-mid M
dwarfs (9.0 0.06 M_sun.Comment: 24 pages, 5 figures, accepted for publication in Ap
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