627 research outputs found
Disorder-driven superconductor-normal metal phase transition in quasi-one-dimensional organic conductors
Effects of non-magnetic disorder on the critical temperature T_c and on
diamagnetism of quasi-one-dimensional superconductors are reported. The energy
of Josephson-coupling between wires is considered to be random, which is
typical for dirty organic superconductors. We show that this randomness
destroys phase coherence between wires and that T_c vanishes discontinuously at
a critical disorder-strength. The parallel and transverse components of the
penetration-depth are evaluated. They diverge at different critical
temperatures T_c^{(1)} and T_c, which correspond to pair-breaking and
phase-coherence breaking respectively. The interplay between disorder and
quantum phase fluctuations is shown to result in quantum critical behavior at
T=0, which manifests itself as a superconducting-normal metal phase transition
of first-order at a critical disorder strength.Comment: 12 pages, 3 figure
Rotating vortex dipoles in ferromagnets
Vortex-antivortex pairs are localized excitations and have been found to be
spontaneously created in magnetic elements. In the case that the vortex and the
antivortex have opposite polarities the pair has a nonzero topological charge,
and it behaves as a rotating vortex dipole. We find theoretically, and confirm
numerically, the form of the energy as a function of the angular momentum of
the system and the associated rotation frequencies. We discuss the process of
annihilation of the pair which changes the topological charge of the system by
unity while its energy is monotonically decreasing. Such a change in the
topological charge affects profoundly the dynamics in the magnetic system. We
finally discuss the connection of our results with Bloch Points (BP) and the
implications for BP dynamics.Comment: 6 pages, 2 figure
Periodic sequences of arbitrage: a tale of four currencies
This paper investigates arbitrage chains involving four currencies and four foreign exchange trader‐arbitrageurs. In contrast with the three‐currency case, we find that arbitrage operations when four currencies are present may appear periodic in nature, and not involve smooth convergence to a ‘balanced’ ensemble of exchange rates in which the law of one price holds. The goal of this article is to understand some interesting features of sequences of arbitrage operations, features which might well be relevant in other contexts in finance and economics
Correction of Experimental Retinal Ischemia by L-Isomer of Ethylmethylhydroxypyridine Malate
An important task of pharmacology and ophtalmology is to find specific and highly effective agents for correcting retinal ischemia. The objective of this study is to increase the effectiveness of pharmacological correction of retinal ischemia by using new 3-hydroxypyridine derivative-L-isomer of ethylmethylhydroxypyridine malat
Classical and relativistic dynamics of supersolids: variational principle
We present a phenomenological Lagrangian and Poisson brackets for obtaining
nondissipative hydrodynamic theory of supersolids. A Lagrangian is constructed
on the basis of unification of the principles of non-equilibrium thermodynamics
and classical field theory. The Poisson brackets, governing the dynamics of
supersolids, are uniquely determined by the invariance requirement of the
kinematic part of the found Lagrangian. The generalization of Lagrangian is
discussed to include the dynamics of vortices. The obtained equations of motion
do not account for any dynamic symmetry associated with Galilean or Lorentz
invariance. They can be reduced to the original Andreev-Lifshitz equations if
to require Galilean invariance. We also present a relativistic-invariant
supersolid hydrodynamics, which might be useful in astrophysical applications.Comment: 22 pages, changed title and content, added reference
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