1,342,484 research outputs found
Band structure of (Sr3Sc2O5)Fe2As2 as a possible parent phase for new FeAs superconductors
By means of first-principles FLAPW-GGA calculations, we have investigated the
electronic properties of the newly synthesized layered phase -
(Sr3Sc2O5)Fe2As2. The electronic bands, density of states and Fermi surface
have been evaluated. The resembling of our data for (Sr3Sc2O5)Fe2As2 with band
structure pictures of known FeAs superconducting materials may be considered as
the theoretical background specifying the possibility for (Sr3Sc2O5)Fe2As2 to
become a parent phase for new FeAs superconductors.Comment: 10 pages, 4 figures, 3 table
On upstream influence in supersonic flows
The general problem of propagation of three-dimensional disturbances in viscous supersonic flows is considered in the framework of characteristic analysis. Unlike previous results for linear disturbances we deduce a condition determining nonlinear characteristic surfaces which is exact and therefore allows both qualitative and quantitative studies of the speed of propagation as a function of various physical phenomena. These include negative and adverse pressure gradients, and effects of wall cooling and suction–blowing, which are studied in this work as an illustration of the general theory
On the infeasibility of entanglement generation in Gaussian quantum systems via classical control
This paper uses a system theoretic approach to show that classical linear
time invariant controllers cannot generate steady state entanglement in a
bipartite Gaussian quantum system which is initialized in a Gaussian state. The
paper also shows that the use of classical linear controllers cannot generate
entanglement in a finite time from a bipartite system initialized in a
separable Gaussian state. The approach reveals connections between system
theoretic concepts and the well known physical principle that local operations
and classical communications cannot generate entangled states starting from
separable states.Comment: 6 pages, 3 figures. To appear in IEEE Transactions on Automatic
Control, 201
Comment on `Measurement of the analyzing power at 68.3 MeV'
We comment on a recent paper by Weiser et al. [Phys. Rev. C {\bf 54}, 1930
(1996)]. The authors have performed a single-energy analysis of
scattering data at 68.3 MeV, finding a value for the phase shift about
1^o smaller than found in the Karlsruhe-Helsinki (KH) partial-wave analysis.
The authors use this result to argue for a dispersion relation analysis using
recently measured data, so that their effect on the coupling constant
(f^2) and amplitude can be determined. We note that these tasks were
accomplished prior to the submission of the above paper. We clarify the effect
of this new analyzing power data on f^2 and the amplitude.Comment: 5 pages of text. Revised according to Referee suggestion
Nanomechanics of a magnetic shuttle device
We show that self sustained mechanical vibrations in a model magnetic shuttle device can be driven by both the charge and the spin accumulated on the movable central island of the device. Different scenarios for how spin- and charge-induced shuttle instabilities may develop are discussed and shown to depend on whether there is a Coulomb blockade of tunneling or not. The crucial role of electronic spin flips in a magnetically driven shuttle is established and shown to cause giant magnetoresistance and dynamic magnetostriction effects
Influence of electric fields on dielectric properties of GPI ferroelectric
Using modified microscopic model of GPI by taking into account the
piezoelectric coupling with strains in the frames of
two-particle cluster approximation, the components of polarization vector and
static dielectric permittivity tensor of the crystal at applying the external
transverse electric fields and are calculated. An analysis of the
influence of these fields on thermodynamic characteristics of GPI is carried
out. A satisfactory quantitative description of the available experimental data
for these characteristics has been obtained at a proper choice of the model
parameters.Comment: 17 pages, 17 figure
Nondispersive X-ray emission analysis for geochemical exploration
Nondispersive X-ray emission technique uses lightweight, and rugged X-ray fluorescence units. The X-ray pulse-height spectra is excited by radioactive isotope sources. The technique is applicable for quantitative and qualitative analyses on complex chemical systems, and satisfies the goals for a lunar geochemical exploration device
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