3,439 research outputs found
Chiral Skyrmionic matter in non-centrosymmetric magnets
Axisymmetric magnetic strings with a fixed sense of rotation and nanometer
sizes (chiral magnetic vortices or Skyrmions) have been predicted to exist in a
large group of non-centrosymmetric crystals more than two decades ago. Recently
these extraordinary magnetic states have been directly observed in thin layers
of cubic helimagnet (Fe,Co)Si. In this report we apply our earlier theoretical
findings to review main properties of chiral Skyrmions, to elucidate their
physical nature, and to analyse these recent experimental results on
magnetic-field-driven evolution of Skyrmions and helicoids in chiral
helimagnets.Comment: 13 pages, 7 figures, invited talk - JEMS-2010 ( 23-28 August, Krakow,
Poland
Evaluation of the current state of aquatic ecosystems and the problems of the protection of biological resources during development of kruzenshternskoye gcf
The results of studies of the current state of freshwater ecosystems and their biotic components in the western part of the Yamal Peninsula are presented in the article. Based on the evaluation of the structure of communities of phytoplankton, zooplankton, benthos, and whitefishes, the range of problems related to the protection of biological resources during the development of the Kruzenshternskoye gas field is defined. The data on species composition and quantitative indicators of hydrobionts of different types of waterbodies and watercourses in the lower reaches of the Mordyyakha and Naduyyakha Rivers basins is the basis for environmental monitoring of water objects during development and exploitation of the Kruzenshternskoye gas field. Estimation of the fish fauna state and their food base in the territory of the Kruzenshternskoye GCF according to the monitoring program is present. The river delta zones are the most important feeding areas of the salmonid and whitefishes valuable fish species in the territory of Kruzenshternskoye GCF. In cases where water bodies and watercourses are not completely demolished for the construction of GCF facilities, changes of quantitative and qualitative characteristics of communities of hydrobionts after the end of operations are reversible. River ecosystems are restored within a shorter period of time in comparison to lacustrine ones. Proposals for the protection of fisheries resources and monitoring of aquatic ecosystems on the basis of comprehensive studies are reported. Recommendations on reducing the anthropogenic impact on aquatic ecosystems in the development period are present. The results of the investigation were used in the development of the environmental protection part of the Kruzenshternskoye deposit project. Anthropogenic disturbances present now on the gas deposit territory of Kruzenshternskoye does not influence the aquatic ecosystems.The article have been prepared within the Project of the Presidium of the Russian Academy of Sciences № 12-P-47-2013 and "The Arctic" Project of the Presidium of the Ural Branch of the Russian Academy of Sciences № 12-4-3-012
On graphs with a large chromatic number containing no small odd cycles
In this paper, we present the lower bounds for the number of vertices in a
graph with a large chromatic number containing no small odd cycles
Dunajski generalization of the second heavenly equation: dressing method and the hierarchy
Dunajski generalization of the second heavenly equation is studied. A
dressing scheme applicable to Dunajski equation is developed, an example of
constructing solutions in terms of implicit functions is considered. Dunajski
equation hierarchy is described, its Lax-Sato form is presented. Dunajsky
equation hierarchy is characterized by conservation of three-dimensional volume
form, in which a spectral variable is taken into account.Comment: 13 page
Statistical Estimation of Quantum Tomography Protocols Quality
A novel operational method for estimating the efficiency of quantum state
tomography protocols is suggested. It is based on a-priori estimation of the
quality of an arbitrary protocol by means of universal asymptotic fidelity
distribution and condition number, which takes minimal value for better
protocol. We prove the adequacy of the method both with numerical modeling and
through the experimental realization of several practically important protocols
of quantum state tomography
A Performance and Resource Consumption Assessment of Secure Multiparty Computation
In recent years, secure multiparty computation (SMC) advanced from a
theoretical technique to a practically applicable technology. Several
frameworks were proposed of which some are still actively developed.
We perform a first comprehensive study of performance characteristics of SMC
protocols using a promising implementation based on secret sharing, a common
and state-of-the-art foundation. Therefor, we analyze its scalability with
respect to environmental parameters as the number of peers, network properties
-- namely transmission rate, packet loss, network latency -- and
parallelization of computations as parameters and execution time, CPU cycles,
memory consumption and amount of transmitted data as variables.
Our insights on the resource consumption show that such a solution is
practically applicable in intranet environments and -- with limitations -- in
Internet settings
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