10,772 research outputs found
Comment on "Interaction Effects in Conductivity of Si Inversion Layers at Intermediate Temperatures"
We show that the comparison between theory and experiment, performed by
Pudalov et al. in PRL 91, 126403 (2003), is not valid.Comment: comment on PRL 91, 126403 (2003) by Pudalov et a
Magnetoresistance of a two-dimensional electron gas in a parallel magnetic field
The conductivity of a two-dimensional electron gas in a parallel magnetic
field is calculated. We take into account the magnetic field induced
spin-splitting, which changes the density of states, the Fermi momentum and the
screening behavior of the electron gas. For impurity scattering we predict a
positive magnetoresistance for low electron density and a negative
magnetoresistance for high electron density. The theory is in qualitative
agreement with recent experimental results found for Si inversion layers and Si
quantum wells.Comment: 4 pages, figures included, PDF onl
Tomography of the red supergiant star {\mu} Cep
A tomographic method, aiming at probing velocity fields at depth in stellar
atmospheres, is applied to the red supergiant star {\mu} Cep and to snapshots
of 3D radiative-hydrodynamics simulation in order to constrain atmospheric
motions and relate them to photometric variability.Comment: 2 pages, 2 figures, accepted as Proceedings of IAU Symposium No. 343,
201
Multifractal detrended cross-correlation analysis for two nonstationary signals
It is ubiquitous in natural and social sciences that two variables, recorded
temporally or spatially in a complex system, are cross-correlated and possess
multifractal features. We propose a new method called multifractal detrended
cross-correlation analysis (MF-DXA) to investigate the multifractal behaviors
in the power-law cross-correlations between two records in one or higher
dimensions. The method is validated with cross-correlated 1D and 2D binomial
measures and multifractal random walks. Application to two financial time
series is also illustrated.Comment: 4 RevTex pages including 6 eps figure
Magnetic Field Suppression of the Conducting Phase in Two Dimensions
The anomalous conducting phase that has been shown to exist in zero field in
dilute two-dimensional electron systems in silicon MOSFETs is driven into a
strongly insulating state by a magnetic field of about 20 kOe applied parallel
to the plane. The data suggest that in the limit of T -> 0 the conducting phase
is suppressed by an arbitrarily weak magnetic field. We call attention to
striking similarities to magnetic field-induced superconductor-insulator
transitions
A New Liquid Phase and Metal-Insulator Transition in Si MOSFETs
We argue that there is a new liquid phase in the two-dimensional electron
system in Si MOSFETs at low enough electron densities. The recently observed
metal-insulator transition results as a crossover from the percolation
transition of the liquid phase through the disorder landscape in the system
below the liquid-gas critical temperature. The consequences of our theory are
discussed for variety of physical properties relevant to the recent
experiments.Comment: 12 pages of RevTeX with 3 postscript figure
Flow diagram of the metal-insulator transition in two dimensions
The discovery of the metal-insulator transition (MIT) in two-dimensional (2D)
electron systems challenged the veracity of one of the most influential
conjectures in the physics of disordered electrons, which states that `in two
dimensions, there is no true metallic behaviour'; no matter how weak the
disorder, electrons would be trapped and unable to conduct a current. However,
that theory did not account for interactions between the electrons. Here we
investigate the interplay between the electron-electron interactions and
disorder near the MIT using simultaneous measurements of electrical resistivity
and magnetoconductance. We show that both the resistance and interaction
amplitude exhibit a fan-like spread as the MIT is crossed. From these data we
construct a resistance-interaction flow diagram of the MIT that clearly reveals
a quantum critical point, as predicted by the two-parameter scaling theory
(Punnoose and Finkel'stein, Science 310, 289 (2005)). The metallic side of this
diagram is accurately described by the renormalization group theory without any
fitting parameters. In particular, the metallic temperature dependence of the
resistance sets in when the interaction amplitude reaches gamma_2 = 0.45 - a
value in remarkable agreement with the one predicted by the theory.Comment: as publishe
AUTOMATED COMPUTER SYSTEM FOR INTERACTIVE COMMUNICATION WITH А DRIVER
The electronic system which serves for the convenience of driving and improve neut of traffic safety has been regarded. Innovative development of an integrated system of voice control with the possibility of interactive communication and the function of preventing from falling asleep has been given
- …