276 research outputs found
Biodiversity of Small Mammals and Paleoenvironment of Transbaikalia and North Mongolia in the Late Pliocene
This paper reports the results of analysis on small mammal faunas dwelling during the Late Pliocene the Transbaikal and Northern Mongolia regions. They were found to share many common species, even though some differences linked with local and regional specifics of the environment are the case. High diversity of small mammal taxa, species richness and their prominent quantity specify the localities of Udunga, Beregovaya and Tologoi in Transbaikal region and in Shamar of Northern Mongolia. The compositions of all faunas point to the existence of the savanna-like landscapes and warm semiarid climate in that period
Orbital and physical parameters of the spectroscopic binary HD37737
We report the physical and orbital parameters of the visible component of the spectroscopic binary HD37737 (m V = 8.03). The observations were performed with the 1.2-m telescope of the Kourovka Astronomical Observatory of the Ural Federal University in 2012 and the 6-m BTA telescope of the SAO RAS in 2007 and 2009. Radial velocities were measured separately from each spectral line of the list by the cross-correlation method with a synthetic spectrum. The latter was calculated using the grids of non-LTE model atmospheres with solar chemical compositions. A significant difference in the epochs of observations (2005-2012) allowed to refine the orbital period of the star (7· d84705) and the orbital elements of the binary system. We obtained an estimate of the mass function f(m) = 0.23 ± 0.02M ⊙. The best agreement between the synthetic and observed spectra is achieved at T eff = 30 000 K and log g = 3.50 according to the observations on both instruments. The obtained parameters correspond to a star of spectral type O9.5 III, with mass estimated at 26 ± 2M ⊙. The minimum mass estimate of the secondary component of the binary is 6.2 ± 0.5M ⊙. We have discovered a fact that the velocities, obtained from different spectral lines, differ, which is typical for giant stars. Engaging additional spectra, obtained in 2005 with the 2.1-m KPNO telescope, we investigated the effect of this fact on the estimate of the speed of the system's center of mass. The difference in the velocities of various lines is approximately the same in the spectra, obtained at all the three instruments. The obtained ratios suggest that the deeper layers of the atmosphere of the star are moving with a greater velocity than the outer layers. Depending on the line, the estimate of the heliocentric velocity of the binary's center of mass varies in the range from -11 to 1 km/s. © 2013 Pleiades Publishing, Ltd
Impurity-induced stabilization of solitons in arrays of parametrically driven nonlinear oscillators
Chains of parametrically driven, damped pendula are known to support
soliton-like clusters of in-phase motion which become unstable and seed
spatiotemporal chaos for sufficiently large driving amplitudes. We show that
the pinning of the soliton on a "long" impurity (a longer pendulum) expands
dramatically its stability region whereas "short" defects simply repel solitons
producing effective partition of the chain. We also show that defects may
spontaneously nucleate solitons.Comment: 4 pages in RevTeX; 7 figures in ps forma
Magnetic force microscopy of atherosclerotic plaque.
In this work by methods of scanning probe microscopy, namely by atomic force microscopy and magnetic force microscopy the fragments of atherosclerotic plaque section of different nature were investigated. The fragments of atherosclerotic vessels with elements of immature plaque were taken during the coiled artery bypass surgery by alloprosthesis. As the result of investigation we found magnetically ordered phase of endogenous origin in the fragment of solid plaque of mixed structure. This phase is presents biogenic magnetic nanoparticles and their clusters with average size characteristic of 200-400 nm
Terahertz Bloch oscillator with a modulated bias
Electrons performing Bloch oscillations in an energy band of a dc-biased
superlattice in the presence of weak dissipation can potentially generate THz
fields at room temperature. The realization of such Bloch oscillator is a
long-standing problem due to the instability of a homogeneous electric field in
conditions of negative differential conductivity. We establish the theoretical
feasibility of stable THz gain in a long superlattice device in which the bias
is quasistatically modulated by microwave fields. The modulation waveforms must
have at least two harmonics in their spectra.Comment: 5 page
Two and three-dimensional oscillons in nonlinear Faraday resonance
We study 2D and 3D localised oscillating patterns in a simple model system
exhibiting nonlinear Faraday resonance. The corresponding amplitude equation is
shown to have exact soliton solutions which are found to be always unstable in
3D. On the contrary, the 2D solitons are shown to be stable in a certain
parameter range; hence the damping and parametric driving are capable of
suppressing the nonlinear blowup and dispersive decay of solitons in two
dimensions. The negative feedback loop occurs via the enslaving of the
soliton's phase, coupled to the driver, to its amplitude and width.Comment: 4 pages; 1 figur
Suppressed absolute negative conductance and generation of high-frequency radiation in semiconductor superlattices
We show that space-charge instabilities (electric field domains) in
semiconductor superlattices are the attribute of absolute negative conductance
induced by small constant and large alternating electric fields. We propose the
efficient method for suppression of this destructive phenomenon in order to
obtain a generation at microwave and THz frequencies in devices operating at
room temperature. We theoretically proved that an unbiased superlattice with a
moderate doping subjected to a microwave pump field provides a strong gain at
third, fifth, seventh, etc. harmonics of the pump frequency in the conditions
of suppressed domains.Comment: 8 pages. Development of cond-mat/0503216 . Version 2: Final version,
erratum is include
ANALYSIS OF THE MARKETING POTENTIAL OF ENRICHED FOOD PRODUCTS FOR PREGNANT WOMEN
The article presents the results of the analysis of the marketing potential of fortified food products for the nutrition of women during breastfeeding and pregnancy. Catering for pregnant women is one of the important conditions for the normal pregnancy, stable functioning of the organs and systems of a woman during this difficult period and the birth of a healthy baby. There is a deficiency of a wide range of nutrients in pregnant and lactating women in various regions of Russia, so this problem solution can be considered a very promising direction in the state food industry.In the course of marketing research, a simultaneous cross-sectional study has been carried out, the possibility of using a food enrichment system from domestic raw materials of deep processing to produce an assortment of functional pastes has been assessed. The demand for the developed product line of products in the market has been studied and a target audience has been revealed.The calculations of the optimal price level for fortified products for the therapeutic and prophylactic nutrition of pregnant women are presented, the range of retail prices per unit of finished product has been determined. The potential market capacity has been estimated, the values obtained in answering the questions of marketing research have been taken as an assumption. The results obtained indicate that the increase in the price of developed finished products compared to traditional don’t not go beyond the purchasing power of the target audience. At the same time, the proposed product line of pastes with a therapeutic and prophylactic orientation will make it possible to correct violations of female homeostasis during pregnancy and breastfeedin
Subterahertz chaos generation by coupling a superlattice to a linear resonator
We investigate the effects of a linear resonator on the high-frequency dynamics of electrons in devices exhibiting negative differential conductance. We show that the resonator strongly affects both the dc and ac transport characteristics of the device, inducing quasiperiodic and high-frequency chaotic current oscillations. The theoretical findings are confirmed by experimental measurements of a GaAs=AlAs miniband semiconductor superlattice coupled to a linear microstrip resonator. Our results are applicable to other active solid state devices and provide a generic approach for developing modern chaos-based high-frequency technologies including broadband chaotic wireless communication and superfast random-number generation
- …