20 research outputs found
Hall Coefficient in an Interacting Electron Gas
The Hall conductivity in a weak homogeneous magnetic field, , is calculated. We have shown that to leading order in
the Hall coefficient is not renormalized by the
electron-electron interaction. Our result explains the experimentally observed
stability of the Hall coefficient in a dilute electron gas not too close to the
metal-insulator transition. We avoid the currently used procedure that
introduces an artificial spatial modulation of the magnetic field. The problem
of the Hall effect is reformulated in a way such that the magnetic flux
associated with the scattering process becomes the central element of the
calculation.Comment: 23 pages, 15 figure
2D superconductivity with strong spin-orbit interaction
We consider superconductivity confined at a two-dimensional interface with a
strong surface spin-orbit (Rashba) interaction. Some peculiar properties of
this system are investigated. In particular, we show that an in-plane Zeeman
field can induce a supercurrent flow.Comment: latex, 1 figure in ep
Generation of spin-polarized currents in Zeeman-split Tomonaga-Luttinger models
In a magnetic field an interacting electron gas in one dimension may be
described as a Tomonaga-Luttinger model comprising two components with
different Fermi velocities due to the Zeeman splitting. This destroys the
spin-charge separation, and even the quantities such as the density-density
correlation involve spin and charge critical exponents (K). Specifically, the
ratio of the up-spin and down-spin conductivities in a dirty system diverges at
low temperatures like an inverse power of the temperature,
, resulting in a spin-polarized current. In
finite, clean systems the conductance becomes different for up- and down-spins
as another manifestation of the electron-electron interaction.Comment: 10 pages, RevTeX file, 3 figures available on request from
[email protected]
Weak localization and conductance fluctuations of a chaotic quantum dot with tunable spin-orbit coupling
In a two-dimensional quantum dot in a GaAs heterostructure, the spin-orbit
scattering rate is substantially reduced below the rate in a bulk
two-dimensional electron gas [B.I. Halperin et al, Phys. Rev. Lett. 86, 2106
(2001)]. Such a reduction can be undone if the spin-orbit coupling parameters
acquire a spatial dependence, which can be achieved, e.g., by a metal gate
covering only a part of the quantum dot. We calculate the effect of such
spatially non-uniform spin-orbit scattering on the weak localization correction
and the universal conductance fluctuations of a chaotic quantum dot coupled to
electron reservoirs by ballistic point contacts, in the presence of a magnetic
field parallel to the plane of the quantum dot.Comment: 4 pages, RevTeX; 2 figures. Substantial revision
Antimicrobial drug resistance mechanisms among Mollicutes
Representatives of the Mollicutes class are the smallest, wall-less bacteria capable of independent reproduction. They are widespread in nature, most are commensals, and some are pathogens of humans, animals and plants. They are also the main contaminants of cell cultures and vaccine preparations. Despite limited biosynthetic capabilities, they are highly adaptable and capable of surviving under various stress and extreme conditions, including antimicrobial selective pressure. This review describes current understanding of antibiotic resistance (ABR) mechanisms in Mollicutes. Protective mechanisms in these bacteria include point mutations, which may include non-target genes, and unique gene exchange mechanisms, contributing to transfer of ABR genes. Better understanding of the mechanisms of emergence and dissemination of ABR in Mollicutes is crucial to control these hypermutable bacteria and prevent the occurrence of highly ABR strains
Best proximity points: global optimal approximate solutions
Global optimal approximate solution, Fixed point, Best proximity point, Contractive mapping,