435 research outputs found
Superflare G and K Stars and the Lithium abundance
We analyzed here the connection of superflares and the lithium abundance in G
and K stars based on Li abundance determinations conducted with the echelle
spectra of a full set of 280 stars obtained with the ELODIE spectrograph. For
high-active stars we show a definite correlation between and the
chromosphere activity. We show that sets of stars with high Li abundance and
having superflares possess common properties. It relates, firstly, to stars
with activity saturation. We consider the X-ray data for G, K, and M stars
separately, and show that transition from a saturation mode to solar-type
activity takes place at values of rotation periods 1.1, 3.3, and 7.2 days for
G2, K4 and M3 spectral types, respectively. We discuss bimodal distribution of
a number of G and K main-sequence stars versus an axial rotation and location
of superflare stars with respect to other Kepler stars. We conclude that
superflare G and K stars are mainly fast rotating young objects, but some of
them belong to stars with solar-type activity. At the same time, we found a
group of G stars with high Li content , but being
slower rotators with rotation periods > 10 days, which are characterized by low
chromospheric activity. This agrees with a large spread in Li abundances in
superflare stars. A mechanism leading to this effect is discussed.Comment: 6 pages, 8 figures. The 19th Cambridge Workshop on Cool Stars,
Stellar Systems, and the Su
Oxygen profiles in membranes.
AbstractTransmembrane profiles of molecular oxygen in lipid bilayers are not only significant for membrane physiology and pathology, but also are essential to the determination of membrane protein structure by site-directed spin labeling. Oxygen profiles obtained with spin-labeled lipid chains have a Boltzmann sigmoidal dependence on the depth into each lipid leaflet, which represents a two-compartment distribution between outer and inner regions of the membrane, with a transfer free energy that depends linearly on distance from the dividing planes. Transmembrane profiles for intramembrane polarity, and for water penetration into the membrane, have an identical form, but are of the reverse sign. Comparison with recently published oxygen profiles from a site-specifically spin-labeled α-helical transmembrane peptide validates the use of spin-labeled lipids for all these profiles and provides the necessary bridge to generate the full bilayer from a single lipid leaflet
Anisotropic motion effects in CW non-linear EPR spectra: relaxation enhancement of lipid spin labels
Mechanism of relaxation enhancement of spin labels in membranes by paramagnetic ion salts: dependence on 3 d and 4 f ions and on the anions.
Fractional Models of Cosmic Ray Acceleration in the Galaxy
Possible formulations of the problem of cosmic rays acceleration in the
interstellar galactic medium are considered with the use of fractional
differential equations. The applied technique has been physically justified. A
Fermi result has been generalized to the case of the acceleration of particles
in shock waves in the supernovae remnants fractally distributed in the Galaxy.Comment: 10 page
An analysis of quadrupole splitting of the Mössbauer spectra of ferritin and iron-dextran complexes in relation to the iron core microstructural variations
Mössbauer spectra of human liver ferritin and some pharmaceutically important iron-dextran complexes as ferritin models were measured at 87 K (frozen solutions) and at both 87 and 295 K (lyophilized forms). The Mössbauer spectra consisted of paramagnetic doublets only. However, the spectral line shapes were not Lorentzian and these Mössbauer spectra were better fitted using a superposition of two or more quadrupole doublets or using a distribution of quadrupole splittings. The differences of the maximal quantity of quadrupole doublets for better fitting of various Mössbauer spectra of ferritin and iron-dextran complexes were compared with the fitting using the distribution of quadrupole splitting for additional analysis. It is possible that variations of the quantity of quadrupole doublets for better fitting of Mössbauer spectra of ferritin and iron-dextran complexes may be related to heterogeneous iron cores in the samples. This heterogeneity is supposed to be different for various samples and changed for lyophilized samples and for frozen solutions as well as for various temperatures
Features of spatial distribution of oscillations in faculae regions
We found that oscillations of LOS velocity in H-alpha are different for
various parts of faculae regions. Power spectra show that the contribution of
low-frequency modes (1.2 - 2 mHz) increase at the network boundaries. Three and
five- minute periods dominate inside cells. The spectra of photosphere and
chromosphere LOS velocity oscillations differ for most faculae. On the other
hand, we detected several cases where propagating oscillations in faculae were
manifest with a five-minute period. Their initiation point on spatial-temporal
diagrams coincided with the local maximum of the longitudinal magnetic field.Comment: 6 pages, 4 figure
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