Spin excitations of the correlated semiconductor FeSi probed by THz radiation

By direct measurements of the complex optical conductivity $\sigma(\nu)$ of FeSi we have discovered a broad absorption peak centered at frequency $\nu_{0}(4.2 K) \approx 32 cm^{-1}$ that develops at temperatures below 20 K. This feature is caused by spin-polaronic states formed in the middle of the gap in the electronic density of states. We observe the spin excitations between the electronic levels split by the exchange field of $H_{e}=34\pm 6 T$. Spin fluctuations are identified as the main factor determining the formation of the spin polarons and the rich magnetic phase diagram of FeSi.Comment: 5 pages, 4 figure

Game species fodder conditions in Eastern Siberia and Amur region

Hunting farms can serve as a source of primary data on the state of natural resources. Taking into account the increasing anthropogenic impact on the environment, it is necessary to constantly monitor the situation with food for ungulates and predators in order to be able to take timely measures to improve the quality of habitat for wild fauna. Populations of wild large animals live in the host landscapes of so reduced that animals population become extremely vulnerable and unstable, signs of crisis can be seen in the data on the number of animals. Lack of natural food is a serious deterrent, especially in difficult times of the year, such as winter and spring. An analysis of the situation with food for a particular species will allow hunting farms to properly plan their feeding and other activities throughout the year in order to maintain a population of certain species on their territory and minimize the migration of species outside the protected areas. The aim of our work was to create a baseline for tracking data on the characteristics of wildlife animals. The research results allow hunting farms to use the data of animal feeding preferences during different seasons of the year for better organization of their biotechnical measures and improvement of feeding conditions for such species as red deer (Cervus elaphus), elk (Cervus canadensis), roe deer (Capreolus pygargus) and bear(Ursus arctos)

Upper limit on the ultra-high-energy photon flux from AGASA and Yakutsk data

We present the interpretation of the muon and scintillation signals of ultra-high-energy air showers observed by AGASA and Yakutsk extensive air shower array experiments. We consider case-by-case ten highest energy events with known muon content and conclude that at the 95% confidence level (C.L.) none of them was induced by a primary photon. Taking into account statistical fluctuations and differences in the energy estimation of proton and photon primaries, we derive an upper limit of 36% at 95% C.L. on the fraction of primary photons in the cosmic-ray flux above 10^20 eV. This result disfavors the Z-burst and superheavy dark-matter solutions to the GZK-cutoff problem.Comment: revtex, 8 pages, 4 figure