17,384 research outputs found
Lax forms of the -Painlev\'e equations
All -Painlev\'e equations which are obtained from the -analog of the
sixth Painlev\'e equation are expressed in a Lax formalism. They are
characterized by the data of the associated linear -difference equations.
The degeneration pattern from the -Painlev\'e equation of type is also
presented.Comment: 24 page
Phase mixing of shear Alfvén waves as a new mechanism for electron acceleration in collisionless, kinetic plasmas
Particle-in-cell (kinetic) simulations of shear Alfv´en wave (AW) interaction with one-dimensional, across the uniform-magnetic field, density inhomogeneity (phase mixing) in collisionless plasma were performed for the first time. As a result, a new electron acceleration mechanism is discovered. Progressive distortion of the AW front, due to the differences in local Alfv´en speed, generates electrostatic fields nearly parallel to the magnetic field, which accelerate electrons via Landau damping. Surprisingly, the amplitude decay law in the inhomogeneous regions, in the kinetic regime, is the same as in the MHD approximation described by Heyvaerts and Priest (1983 Astron. Astrophys. 117 220)
Field induced transition of the S=1 antiferromagnetic chain with anisotropy
The ground state magnetization process of the S=1 antiferromagnetic chain
with the easy-axis single-ion anisotropy described by negative is
investigated. It is numerically found that a phase transition between two
different gapless phases occurs at an intermediate magnetic field between the
starting and saturation points of the magnetization for . The
transition is similar to the spin flopping, but it is second-order and not
accompanied with any significant anomalous behaviors in the magnetization
curve. We also present the phase diagrams in the m-D and H-D planes which
reveal a possible re-entrant transition.Comment: 6 pages, Revtex, with 6 eps figures, to appear in Phys. Rev. B (Sep.
1
Single domain YBCO/Ag bulk superconductors fabricated by seeded infiltration and growth
We have applied the seeded infiltration and growth (IG) technique to the processing of samples containing Ag in an attempt to fabricate Ag-doped Y-Ba-Cu-O (YBCO) bulk superconductors with enhanced mechanical properties. The IG technique has been used successfully to grow bulk Ag-doped YBCO superconductors of up to 25 mm in diameter in the form of single grains. The distribution of Ag in the parent Y-123 matrix fabricated by the IG technique is observed to be at least as uniform as that in samples grown by conventional top seeded melt growth (TSMG). Fine Y-211 particles were observed to be embedded within the Y-123 matrix for the IG processed samples, leading to a high critical current density, Jc, of over 70 kA/cm2 at 77.3 K in self-field. The distribution of Y-211 in the IG sample microstructure, however, is inhomogeneous, which leads to a variation in the spatial distribution of Jc throughout the bulk matrix. A maximum-trapped field of around 0.43 T at 1.2 mm above the sample surface (i.e. including 0.7 mm for the sensor mould thickness) is observed at liquid nitrogen temperature, despite the relatively small grain size of the sample (20 mm diameter × 7 mm thickness)
Operator Analysis for Proton Decay in SUSY SO(10) GUT Models
Non-renormalizable operators both account for the failure of down quark and
charged lepton Yukawa couplings to unify and reduce the proton decay rate via
dimension-five operators in minimal SUSY SU(5) GUT. We extend the analysis to
SUSY SO(10) GUT models.Comment: Higgs sector clarified, two Refs adde
An investigation of children's peer trust across culture: is the composition of peer trust universal?
The components of children's trust in same-gender peers (trust beliefs, ascribed trustworthiness, and dyadic reciprocal trust) were examined in samples of 8- to 11-year-olds from the UK, Italy, and Japan. Trust was assessed by children's ratings of the extent to which same-gender classmates kept promises and kept secrets. Social relations analyses confirmed that children from each country showed significant: (a) actor variance demonstrating reliable individual differences in trust beliefs, (b) partner variance demonstrating reliable individual differences in ascribed trustworthiness, and (c ) relationship variance demonstrating unique relationships between interaction partners. Cultural differences in trust beliefs and ascribed trustworthiness also emerged and these differences were attributed to the tendency for children from cultures that value societal goals to share personal information with the peer group
Gap formation and soft phonon mode in the Holstein model
We investigate electron-phonon coupling in many-electron systems using
dynamical mean-field theory in combination with the numerical renormalization
group. This non-perturbative method reveals significant precursor effects to
the gap formation at intermediate coupling strengths. The emergence of a soft
phonon mode and very strong lattice fluctuations can be understood in terms of
Kondo-like physics due to the development of a double-well structure in the
effective potential for the ions
Metamagnetism of antiferromagnetic XXZ quantum spin chains
The magnetization process of the one-dimensional antiferromagnetic Heisenberg
model with the Ising-like anisotropic exchange interaction is studied by the
exact diagonalization technique. It results in the evidence of the first-order
spin flop transition with a finite magnetization jump in the N\'eel ordered
phase for . It implies that the S=1/2 chain is an exceptional case
where the metamagnetic transition becomes second-order due to large quantum
fluctuations.Comment: 4 pages, Revtex, with 6 eps figure
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