160 research outputs found
The role of the Fraunhofer lines in solar brightness variability
The solar brightness varies on timescales from minutes to decades. A clear
identification of the physical processes behind such variations is needed for
developing and improving physics-based models of solar brightness variability
and reconstructing solar brightness in the past. This is, in turn, important
for better understanding the solar-terrestrial and solar-stellar connections.
We estimate the relative contributions of the continuum, molecular, and
atomic lines to the solar brightness variations on different timescales.
Our approach is based on the assumption that variability of the solar
brightness on timescales greater than a day is driven by the evolution of the
solar surface magnetic field. We calculated the solar brightness variations
employing the solar disc area coverage of magnetic features deduced from the
MDI/SOHO observations. The brightness contrasts of magnetic features relative
to the quiet Sun were calculated with a non-LTE radiative transfer code as
functions of disc position and wavelength. By consecutive elimination of
molecular and atomic lines from the radiative transfer calculations, we
assessed the role of these lines in producing solar brightness variability.
We show that the variations in Fraunhofer lines define the amplitude of the
solar brightness variability on timescales greater than a day and even the
phase of the total solar irradiance variability over the 11-year cycle. We also
demonstrate that molecular lines make substantial contribution to solar
brightness variability on the 11-year activity cycle and centennial timescales.
In particular, our model indicates that roughly a quarter of the total solar
irradiance variability over the 11-year cycle originates in molecular lines.
The maximum of the absolute spectral brightness variability on timescales
greater than a day is associated with the CN violet system between 380 and 390
nm.Comment: 9 pages, 4 figures, accepted for publication in
Astronomy&Astrophysic
Magnetoresistance of a semiconducting magnetic wire with domain wall
We investigate theoretically the influence of the spin-orbit interaction of
Rashba type on the magnetoresistance of a semiconducting ferromagnetic
nanostructure with a laterally constrained domain wall. The domain wall is
assumed sharp (on the scale of the Fermi wave length of the charge carriers).
It is shown that the magnetoresistance in such a case can be considerably
large, which is in a qualitative agreement with recent experimental
observations. It is also shown that spin-orbit interaction may result in an
increase of the magnetoresistance. The role of localization corrections is also
briefly discussed.Comment: 5 pages, 2 figure
The impact of innovations in the production of biologically valuable food products on supply chain management in the regional economy
Abstract— The article shows a study of the role of supply chain management of innovative biologically valuable food products in the industrial development and economy of the region. The analysis of the process of updating the assortment of food products based on the introduction of innovative developments and production principles conducive to the release of a healthy diet product (innovative product) is presented. The main provisions of the concept of healthy food products, the category of “innovative food products” are analyzed. The article systematizes the definitions of the concept of “innovative product”. Based on the results of the study, features, functional properties and characteristic features of an innovative food product are determined. Based on the concept of “innovative food product”, the concepts of “new food product”, “improved food product”, and “modified food product” are formulated. A classification model of innovative food products is presented. Based on it, it is shown that the development, production and sale of an innovative food product two functions: economic and social. The study made it possible to formulate the main criteria that make it possible to attribute a food product to a group of innovative food products. The article describes the characteristics of an innovative food product, describes market and consumer properties. The author's definitions of concepts are given: “innovative food product”, “new food product”, “improved food product”, “modified food product”. A classification of innovative food products is proposed
Experimental Observation of the Inverse Proximity Effect in Superconductor/Ferromagnet Layered Structures
We have studied the nuclear magnetic resonance (NMR) of 51V nuclei in the
superconductor/ferromagnet thin film heterostructures Ni/V/Ni and
Pd{1-x}Fe{x}/V/Pd{1-x}Fe{x} in the normaland superconducting state. Whereas the
position and shape of the NMR line in the normal state for the trilayers is
identical to that observed in a single V-layer, in the superconducting state
the line shape definitely changes, developing a systematic distortion of the
high-field wing of the resonance line. We consider this as the first
experimental evidence for the penetration of ferromagnetism into the
superconducting layer, a phenomenon which has been theoretically predicted
recently and dubbed the inverse proximity effect.Comment: about 5 pages, 3 figures, 1 tabl
On the hyperfine interaction in rare-earth Van Vleck paramagnets at high magnetic fields
An influence of high magnetic fields on hyperfine interaction in the
rare-earth ions with non-magnetic ground state (Van Vleck ions) is
theoretically investigated for the case of ion in axial symmetrical
crystal electric field (ethylsulphate crystal). It is shown that magnetic-field
induced distortions of -electron shell lead to essential changes in
hyperfine magnetic field at the nucleus. The proposed theoretical model is in
agreement with recent experimental data.Comment: 4 pages, no figures, submitted to J. Phys. : Cond. Mat
Superconducting decay length in a ferromagnetic metal
The complex decay length xi characterizing penetration of superconducting
correlations into a ferromagnet due to the proximity effect is studied
theoretically in the frame of the linearized Eilenberger equations. The real
part xi_1 and imaginary part xi_2 of the decay length are calculated as
functions of exchange energy and the rates of ordinary, spin flip and spin
orbit electronic scattering in a ferromagnet. The lengths xi_1,2 determine the
spatial scales of, respectively, decay and oscillation of a critical current in
SFS Josephson junctions in the limit of large distance between superconducting
electrodes. The developed theory provides the criteria of applicability of the
expressions for xi_1 and xi_2 in the dirty and the clean limits which are
commonly used in the analysis of SF hybrid structures.Comment: 5 pages, 3 figure
Electron paramagnetic resonance and quantitative color investigations of various vacuum heat treated wood species
© Kazan Federal University (KFU). The effect of the heat treatment duration on the electron paramagnetic resonance signal amplitude of free radicals for various wood species was observed. It was found that the amplitude of the electron paramagnetic resonance signal grows linearly with the vacuum heat treatment duration. The quantitative measurements of color changes for various wood species (pine, spruce, larch, birch and small-leaved lime) were performed. It is found that results of EPR experiments and color measurements of heat treated samples correlate with each other
Spin screening effect in superconductor/ferromagnet thin film heterostructures studied using nuclear magnetic resonance
Using NMR spectroscopy of the V 51 nuclei in the superconducting state of Ni/V/Ni and Pd1-x Fex /V/ Pd1-x Fex trilayers we reported in a recent letter an experimental observation of the spin screening effect. This effect, which designates the formation of a spin polarization in the superconducting state, was predicted previously by Bergeret. Here, we extend our earlier experiments by varying the thickness of the superconducting V layer and by applying the magnetic field not only perpendicular to the film plane as in the previous experiments, but also in the parallel direction. For the latter geometry, which for experimental reasons is difficult to realize, the film is in the vortex-free state. This allows a direct quantitative comparison of the experimental screening effect as derived from a characteristic distortion of the high-field wing of the resonance line in the superconducting state and the theoretical model calculations. We derive a reasonable agreement between theory and experiment, confirming the spin screening effect in the superconductor. © 2009 The American Physical Society
Experimental observation of the spin screening effect in superconductor/ferromagnet thin film heterostructures
We have studied the nuclear magnetic resonance (NMR) of V51 nuclei in the superconductor/ferromagnet thin film heterostructures Pd1-xFex/V/Pd1-xFex and Ni/V/Ni in the normal and superconducting state. Whereas the position and shape of the NMR line in the normal state for the trilayers is identical to that observed in a single V layer, in the superconducting state the line shape definitely changes, developing a systematic distortion of the high-field wing of the resonance line. We consider this as the first experimental evidence for the penetration of ferromagnetism into the superconducting layer, a phenomenon which has been theoretically predicted recently and dubbed the spin screening effect. © 2009 The American Physical Society
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