781 research outputs found
On quantum corrections to geodesics in de-Sitter spacetime
We find a coordinate-independent wave-packet solution of the massive
Klein-Gordon equation with the conformal coupling to gravity in the de-Sitter
universe. This solution can locally be represented through the superposition of
positive-frequency plane waves at any space-time point, assuming that the
scalar-field mass is much bigger than the de-Sitter Hubble constant .
The solution is also shown to be related to the two-point function in the
de-Sitter quantum vacuum. Moreover, we study the wave-packet propagation over
cosmological times, depending on the ratio of and . In doing so, we find
that this wave packet propagates like a point-like particle of the same mass if
, but, if otherwise, the wave packet behaves highly non-classically.Comment: final version published in Eur. Phys. J.
Evolutionary relationship of Rickettsiae and mitochondria
AbstractPhylogenetic data support an origin of mitochondria from the α-proteobacterial order Rickettsiales. This high-rank taxon comprises exceptionally obligate intracellular endosymbionts of eukaryotic cells, and includes family Rickettsiaceae and a group of microorganisms termed Rickettsia-like endosymbionts (RLEs). Most detailed phylogenetic analyses of small subunit rRNA and chaperonin 60 sequences consistently show the RLEs to have emerged before Rickettsiaceae and mitochondria sister clades. These data suggest that the origin of mitochondria and Rickettsiae has been preceded by the long-term mutualistic relationship of an intracellular bacterium with a pro-eukaryote, in which an invader has lost many dispensable genes, yet evolved carrier proteins to exchange respiration-derived ATP for host metabolites as envisaged in classic endosymbiont theory
Maximum a posteriori estimation through simulated annealing for binary asteroid orbit determination
This paper considers a new method for the binary asteroid orbit determination
problem. The method is based on the Bayesian approach with a global
optimisation algorithm. The orbital parameters to be determined are modelled
through an a posteriori distribution made of a priori and likelihood terms. The
first term constrains the parameters space and it allows the introduction of
available knowledge about the orbit. The second term is based on given
observations and it allows us to use and compare different observational error
models. Once the a posteriori model is built, the estimator of the orbital
parameters is computed using a global optimisation procedure: the simulated
annealing algorithm. The maximum a posteriori (MAP) techniques are verified
using simulated and real data. The obtained results validate the proposed
method. The new approach guarantees independence of the initial parameters
estimation and theoretical convergence towards the global optimisation
solution. It is particularly useful in these situations, whenever a good
initial orbit estimation is difficult to get, whenever observations are not
well-sampled, and whenever the statistical behaviour of the observational
errors cannot be stated Gaussian like.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Societ
Factors of formation of innovative potential of the enterprises
The decision of tasks of constant economic development of the country is directly connected with development of innovative activity which should provide strengthening of competitiveness of domestic subjects of economic activities. One of prominent aspects thus is the interrelation of innovative activity with the environment. As without doubts influence of results of innovative activity on an ecological condition is one of defining parameters of the further manufacture of innovative products. Under such circumstances there is a necessary efficient control of innovative activity with a view of ecological aspect.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/1344
Simulation of hypersonic flows with equilibrium chemical reactions on graphics processor units
Mechanisms of Microwave Absorption in Carbon Compounds from Shungite
According to SEM, X-ray phase analysis, Raman scattering data features of nanostructural changes in shungite carbon structure were found when processing shungite in 52 % hydrofluoric acid. It is found that conductivity increases up to the values of electrical graphite and absorption of microwave radiation also increases at frequencies up to 40 GHz, which, along with dielectric losses, is due to intense processes of both scattering at laminar carbon structures and absorption of electromagnetic energy.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3365
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