9,600 research outputs found
Generalized BFT Formalism of Electroweak Theory in the Unitary Gauge
We systematically embed the SU(2)U(1) Higgs model in the unitary
gauge into a fully gauge-invariant theory by following the generalized BFT
formalism. We also suggest a novel path to get a first-class Lagrangian
directly from the original second-class one using the BFT fields.Comment: 14 pages, Latex, no figure
Overall Evolution of Realistic Gamma-ray Burst Remnant and Its Afterglow
Conventional dynamic model of gamma-ray burst remnants is found to be
incorrect for adiabatic blastwaves during the non-relativistic phase. A new
model is derived, which is shown to be correct for both radiative and adiabatic
blastwaves during both ultra-relativistic and non-relativistic phase. Our model
also takes the evolution of the radiative efficiency into account. The
importance of the transition from the ultra-relativistic phase to the
non-relativistic phase is stressed.Comment: 9 pages, aasms4 style, 3 ps figures, minor changes, will be published
in Chin. Phys. Let
Collective modes and sound propagation in a p-wave superconductor: SrRuO
There are five distinct collective modes in the recently discovered p-wave
superconductor SrRuO; phase and amplitude modes of the order parameter,
clapping mode (real and imaginary), and spin wave. The first two modes also
exist in the ordinary s-wave superconductors, while the clapping mode with the
energy is unique to SrRuO and couples to the sound
wave. Here we report a theoretical study of the sound propagation in a two
dimensional p-wave superconductor. We identified the clapping mode and study
its effects on the longitudinal and transverse sound velocities in the
superconducting state. In contrast to the case of He, there is no resonance
absorption associated with the collective mode, since in metals , where is the Fermi velocity, {\bf q} is the wave
vector, and is the frequency of the sound wave. However, the velocity
change in the collisionless limit gets modified by the contribution from the
coupling to the clapping mode. We compute this contribution and comment on the
visibility of the effect. In the diffusive limit, the contribution from the
collective mode turns out to be negligible. The behaviors of the sound velocity
change and the attenuation coefficient near in the diffusive limit are
calculated and compared with the existing experimental data wherever it is
possible. We also present the results for the attenuation coefficients in both
of the collisionless and diffusive limits at finite temperatures.Comment: RevTex, 12 pages, 2 figures, Replaced by the published versio
Unusual T_c variation with hole concentration in Bi_2Sr_{2-x}La_xCuO_{6+\delta}
We have investigated the variation with the hole concentration in
the La-doped Bi 2201 system, BiSrLaCuO. It is
found that the Bi 2201 system does not follow the systematics in and
observed in other high- cuprate superconductors (HTSC's). The vs
characteristics are quite similar to what observed in Zn-doped HTSC's. An
exceptionally large residual resistivity component in the inplane resistivity
indicates that strong potential scatterers of charge carriers reside in CuO
planes and are responsible for the unusual variation with , as in the
Zn-doped systems. However, contrary to the Zn-doped HTSC's, the strong scatter
in the Bi 2201 system is possibly a vacancy in the Cu site.Comment: RevTeX, 3 figures, to be published in the Physical Review
Quantum Group, Bethe Ansatz and Bloch Electrons in a Magnetic Field
The wave functions for two dimensional Bloch electrons in a uniform magnetic
field at the mid-band points are studied with the help of the algebraic
structure of the quantum group . A linear combination of its
generators gives the Hamiltonian. We obtain analytical and numerical solutions
for the wave functions by solving the Bethe Ansatz equations, proposed by
Wiegmann and Zabrodin on the basis of above observation. The semi-classical
case with the flux per plaquette is analyzed in detail, by exploring
a structure of the Bethe Ansatz equations. We also reveal the multifractal
structure of the Bethe Ansatz solutions and corresponding wave functions when
is irrational, such as the golden or silver mean.Comment: 30 pages, 11 GIF figures(use xv, or WWW browser
A rice ABC transporter, OsABCC1, reduces arsenic accumulation in the grain
Arsenic (As) is a chronic poison that causes severe skin lesions and cancer. Rice (Oryza sativa L.) is a major dietary source of As; therefore, reducing As accumulation in the rice grain and thereby diminishing the amount of As that enters the food chain is of critical importance. Here, we report that a member of the Oryza sativa C-type ATP-binding cassette (ABC) transporter (OsABCC) family, OsABCC1, is involved in the detoxification and reduction of As in rice grains. We found that OsABCC1 was expressed in many organs, including the roots, leaves, nodes, peduncle, and rachis. Expression was not affected when plants were exposed to low levels of As but was up-regulated in response to high levels of As. In both the basal nodes and upper nodes, which are connected to the panicle, OsABCC1 was localized to the phloem region of vascular bundles. Furthermore, OsABCC1 was localized to the tonoplast and conferred phytochelatin-dependent As resistance in yeast. Knockout of OsABCC1 in rice resulted in decreased tolerance to As, but did not affect cadmium toxicity. At the reproductive growth stage, the As content was higher in the nodes and in other tissues of wild-type rice than in those of OsABCC1 knockout mutants, but was significantly lower in the grain. Taken together, our results indicate that OsABCC1 limits As transport to the grains by sequestering As in the vacuoles of the phloem companion cells of the nodes in rice.open117318Ysciescopu
Monomer-dimer model in two-dimensional rectangular lattices with fixed dimer density
The classical monomer-dimer model in two-dimensional lattices has been shown
to belong to the \emph{``#P-complete''} class, which indicates the problem is
computationally ``intractable''. We use exact computational method to
investigate the number of ways to arrange dimers on
two-dimensional rectangular lattice strips with fixed dimer density . For
any dimer density , we find a logarithmic correction term in the
finite-size correction of the free energy per lattice site. The coefficient of
the logarithmic correction term is exactly -1/2. This logarithmic correction
term is explained by the newly developed asymptotic theory of Pemantle and
Wilson. The sequence of the free energy of lattice strips with cylinder
boundary condition converges so fast that very accurate free energy
for large lattices can be obtained. For example, for a half-filled lattice,
, while and . For , is accurate at least to 10 decimal
digits. The function reaches the maximum value at , with 11 correct digits. This is also
the \md constant for two-dimensional rectangular lattices. The asymptotic
expressions of free energy near close packing are investigated for finite and
infinite lattice widths. For lattices with finite width, dependence on the
parity of the lattice width is found. For infinite lattices, the data support
the functional form obtained previously through series expansions.Comment: 15 pages, 5 figures, 5 table
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