2,580 research outputs found
Applications of Liquid Chromatographic Techniques in the Chemical Characterization of Atmospheric Aerosols.
Assessing the potentiality of Romanian surface waters to produce hydroxyl and nitrite radicals
Studies regarding groundwater quality at rural sites. 2. Photochemical generation of °OH and °NO2 radicals upon UV-A irradiation of nitrate-rich groundwater
Investigation of the Dynamics and Kinetics Involved in Saline Aerosol Generation Under Air Erosion of Pure and Contaminated Halide Salts.
Studies regarding groundwater quality at rural sites. 1. Estimation of the anthropic factor impact by complementary chemical analyses
Inhibition vs. enhancement of the nitrate-induced photo-transformation of organic substrates by the °OH scavengers bicarbonate and carbonate
Photostability and photolability of dissolved organic matter upon irradiation of natural water samples under simulated sunlight
Two-dimensional electron transport in the presence of magnetic flux vortices
We have considered the conductivity properties of a two dimensional electron
gas (2DEG) in two different kinds of inhomogeneous magnetic fields, i.e. a
disordered distribution of magnetic flux vortices, and a periodic array of
magnetic flux vortices. The work falls in two parts. In the first part we show
how the phase shifts for an electron scattering on an isolated vortex, can be
calculated analytically, and related to the transport properties through a
force balance equation. In the second part we present numerical results for the
Hall conductivity of the 2DEG in a periodic array of flux vortices. We find
characteristic peaks in the Hall conductance, when plotted against the filling
fraction. It is argued that the peaks can be interpreted in terms of
``topological charge'' piling up across local and global gaps in the energy
spectrum.Comment: 47 pages, Revtex 3.0, 18 postscript figures can be obtained from our
WWW-server: http://roemer.fys.ku.dk/vortices.htm , or on request from the
Authors. Note that this paper is a thoroughly revised version of
cond-mat/940405
nu=1/2 quantum Hall effect in the Aharonov-Casher geometry in a mesoscopic ring
We study the effect of an electric charge in the middle of a ring of
electrons in a magnetic field such as . In the absence of the
central charge, a residual current should appear due to an Aharanov-Bohm
effect. As the charge varies, periodic currents should appear in the ring. We
evaluate the amplitude of these currents, as well as their period as the
central charge varies. The presence of these currents should be a direct
signature of the existence of a statistical gauge field in the
quantum Hall effect. Numerical diagonalizations for a small number of electrons
on the sphere are also carried out. The numerical results up to 9 electrons are
qualitatively consistent with the mean field picture.Comment: 23 pages,14 included postscript figures, submitted to Phys. Rev.
The Aharonov-Bohm effect for massless Dirac fermions and the spectral flow of Dirac type operators with classical boundary conditions
We compute, in topological terms, the spectral flow of an arbitrary family of
self-adjoint Dirac type operators with classical (local) boundary conditions on
a compact Riemannian manifold with boundary under the assumption that the
initial and terminal operators of the family are conjugate by a bundle
automorphism. This result is used to study conditions for the existence of
nonzero spectral flow of a family of self-adjoint Dirac type operators with
local boundary conditions in a two-dimensional domain with nontrivial topology.
Possible physical realizations of nonzero spectral flow are discussed.Comment: 15 pages, 6 figures. Submitted to Theoretical and Mathematical
Physics. v2: A change has been made to the paragraph describing the previous
work of M. Prokhorov
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