Manifestation Of Fluctuations Research Articles

Quantum Fluctuations of Low Dimensional Bose-Einstein Condensates in Optical Systems

A system of low dimensional condensed ultracold atomic gases inside a field of a laser-driven optical cavity exhibits dispersive optical bistability. During such a process the system also shows quantum fluctuations. Condensate fluctuations are highly manifested particularly in low dimensional systems. In this paper we have investigated the theory and manifestation of fluctuations in quantum optical systems in low dimensional Bose-Einstein condensates. We have described the system using the mean-field approximation. In this study we have verified that low dimensional quantum gases exhibit not only highly fascinating properties but also we have indicated that the use of mean field theory to describe quantum gases in low dimensions is highly restricted since the possibility of generating low dimensional bosonic condensates is dominated by the existence of highly sensitive and intrinsic quantum fluctuations.

SPATIAL AND TEMPORAL VARIABILITY OF DRY STEPPES OF EASTERN MONGOLIA

Spatial-temporal structure and coenotic diversity of dry steppes of Eastern Mongolia was identified by analyzing characteristics of naturally occurring vegetation connection to the regional landscape structure. Different types of combinations of plant communities (phytocoenochores) were determined in the vegetation structure of the Eastern Steppe Station Tumén-Tsogt (in Sukhebator district). Temporal dynamics of steppe ecosystems was defined from the studies of steppe cover fluctuations in 2008. The coenotic role of eight annual plant species that form synusiae in the steppe communities was shown through analysis of species constancy, projective cover, and activity. Knowledge about the trend of successions and the manifestation of fluctuations in vegetation cover is necessary for the development of science-based system of management options to maintain the number and abundance of different plant groups in plant communities. Monitoring the state of natural ecosystems has a major scientific and practical importance, since steppe ecosystems are the basic component of the pasture’s resources of the country.

Method of identification of a fluctuating emitter under the conditions of inadequate statistical coverage of measurements

The natural fluctuations of a radiation field have an amplitude that stands at the limit of the sensitivity of modern detectors; it is therefore necessary to enhance the statistical coverage of the detection process. This is usually accomplished by counting over a sufficiently large column of the phase space of the field. The statistical coverage of measurements in such intervals is extremely low, however, and the solution of the identification problem thus requires that the most representative parameter of the appearance of fluctuations be selected and that it be optimally averaged over the entire volume of the phase space. In this paper, such a parameter is chosen on the basis of the principle of synchronous manifestation of fluctuations in phase space. As an example the authors identify, using this parameter, natural fluctuations of the cosmic and bismuth components of gamma radiation of the atmosphere over water, carried out using NaI detectors. A similar method is employed for K 40, Be 7, and Cs 137.

Interaction between the Earth's Liquid Core and Solid Mantle

HORIZONTAL stresses at the interface where the liquid core of the Earth meets the surrounding solid mantle prevent these two major regions of the Earth from moving independently of one another. Speculations as to the physical nature of these stresses have been made in connexion (a) with the investigation of whether the precessional motion of the mantle is significant as a possible cause of the fluid motions in the core that produce the Earth's magnetic field, and (b) with the interpretation of certain tiny, irregular secular changes in the direction and magnitude of the angular velocity of the mantle as being manifestations of fluctuations in core motions. (The books by Munk and Macdonald1 and Marsden and Cameron2 give extensive lists of pertinent references.)