794 research outputs found
Spin waves in diluted magnetic quantum wells
We study collective spin excitations in two-dimensional diluted magnetic
semiconductors, placed into external magnetic field. Two coupled modes of the
spin waves (the electron and ion modes) are found to exist in the system along
with a number of the ion spin excitations decoupled from the electron system.
We calculate analytically the spectrum of the waves taking into account the
exchange interaction of itinerant electrons both with each other and with
electrons localized on the magnetic ions. The interplay of these interactions
leads to a number of intriguing phenomena including tunable anticrossing of the
modes and a field-induced change in a sign of the group velocity of the ion
mode
Development of a Technique and Method of Testing Aircraft Models with Turboprop Engine Simulators in a Small-scale Wind Tunnel - Results of Tests
This report presents the results of experimental investigations into the interaction between the propellers (Ps) and the airframe of a twin-engine, twin-boom light transport aircraft with a Π-shaped tail. An analysis was performed of the forces and moments acting on the aircraft with rotating Ps. The main features of the methodology for windtunnel testing of an aircraft model with running Ps in TsAGI’s T-102 wind tunnel are outlined.The effect of 6-blade Ps slipstreams on the longitudinal and lateral aerodynamic characteristics as well as the effectiveness of the control surfaces was studied on the aircraft model in cruise and takeoff/landing configurations. The tests were conducted at flow velocities of V∞ = 20 to 50 m/s in the ranges of angles of attack α = -6 to 20 deg, sideslip angles of β = -16 to 16 deg and blade loading coefficient of B 0 to 2.8. For the aircraft of unusual layout studied, an increase in blowing intensity is shown to result in decreasing longitudinal static stability and significant asymmetry of the directional stability characteristics associated with the interaction between the Ps slipstreams of the same (left-hand) rotation and the empennage
Raman Spectroscopy of Oxygen Evolution Catalysts and PSII Manganese Model Compounds
Photosynthesis is the basis of life on earth, and oxygen evolution catalysts are key components of this complicated, yet not fully understood process. Photosystem II, a large membrane bound pigment-protein complex, is the key system that facilitates oxygenic photosynthesis via the oxygen evolving complex (a natural oxygen evolving catalyst). It is a key component in oxygen producing catalysts, which can be used in fields such as energy production and biomimetic catalysts. The oxygen evolution cycle, or Kok cycle going within it is still not studied completely. In this project, we were studying the vibrational (and structural) state of a Manganese model compound for PSII and functioning Ruthenium water oxidizing catalyst. The method for this experiment was Raman spectroscopy at two wavelengths in the visible region: 532nm and 442nm. The results obtained from our Manganese model compound are various Raman spectra which will be analyzed using DFT (Density Function theory) and can now be used to predict vibrations relevant to PSII while insights gained from functioning Ruthenium water oxidizing catalysts give clues to the chemistry of PSII
Improving the quality of barley transcriptome <i>de novo</i> assembling by using a hybrid approach for lines with varying spike and stem coloration
De novo transcriptome assembly is an important stage of RNA-seq data computational analysis. It allows the researchers to obtain the sequences of transcripts presented in the biological sample of interest. The availability of accurate and complete transcriptome sequence of the organism of interest is, in turn, an indispensable condition for further analysis of RNA-seq data. Through years of transcriptomic research, the bioinformatics community has developed a number of assembler programs for transcriptome reconstruction from short reads of RNA-seq libraries. Different assemblers makes it possible to conduct a de novo transcriptome reconstruction and a genome-guided reconstruction. The majority of the assemblers working with RNA-seq data are based on the De Bruijn graph method of sequence reconstruction. However, specif ics of their procedures can vary drastically, as do their results. A number of authors recommend a hybrid approach to transcriptome reconstruction based on combining the results of several assemblers in order to achieve a better transcriptome assembly. The advantage of this approach has been demonstrated in a number of studies, with RNA-seq experiments conducted on the Illumina platform. In this paper, we propose a hybrid approach for creating a transcriptome assembly of the barley Hordeum vulgare isogenic line Bowman and two nearly isogenic lines contrasting in spike pigmentation, based on the results of sequencing on the IonTorrent platform. This approach implements several de novo assemblers: Trinity, Trans-ABySS and rnaSPAdes. Several assembly metrics were examined: the percentage of reference transcripts observed in the assemblies, the percentage of RNA-seq reads involved, and BUSCO scores. It was shown that, based on the summation of these metrics, transcriptome meta-assembly surpasses individual transcriptome assemblies it consists of
High-temperature Aharonov-Bohm-Casher interferometer
We study theoretically the combined effect of the spin-orbit and Zeeman
interactions on the tunneling electron transport through a single-channel
quantum ring threaded by magnetic flux. We focus on the high temperature case
(temperature is much higher than the level spacing in the ring) and demonstrate
that spin-interference effects are not suppressed by thermal averaging. In the
absence of the Zeeman coupling the high-temperature tunneling conductance of
the ring exhibits two types of oscillations: Aharonov-Bohm oscillations with
magnetic flux and Aharonov-Casher oscillations with the strength of the
spin-orbit interaction. For weak tunneling coupling both oscillations have the
form of sharp periodic antiresonances. In the vicinity of the antiresonances
the tunneling electrons acquire spin polarization, so that the ring serves as a
spin polarizer. We also demonstrate that the Zeeman coupling leads to
appearance of two additional peaks both in the tunneling conductance and in the
spin polarization
Multifragmentation in Collisions of 4.4gev-Deuterons with Gold Target
The relative velocity correlation function of pairs of intermediate mass
fragments has been studied for d+Au collitions at 4.4 GeV. Experimental
correlation functions are compared to that obtained by multibody Coulomb
trajectory calculations under the assumption of various decay timees of the
fragmenting system. The combined approach with the empirically modified
intranuclear cascade code followed by the statistical multifragmentation model
was used to generate the starting conditions for these calculations. The
fragment emossion time is found to be less than 40 fm/c.Comment: Accepted for publication in Bulletin of the Russian Academy of
Sciences. Physic
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