136 research outputs found
Anomalous diffusion in the dynamics of complex processes
Anomalous diffusion, process in which the mean-squared displacement of system
states is a non-linear function of time, is usually identified in real
stochastic processes by comparing experimental and theoretical displacements at
relatively small time intervals. This paper proposes an interpolation
expression for the identification of anomalous diffusion in complex signals for
the cases when the dynamics of the system under study reaches a steady state
(large time intervals). This interpolation expression uses the chaotic
difference moment (transient structural function) of the second order as an
average characteristic of displacements. A general procedure for identifying
anomalous diffusion and calculating its parameters in real stochastic signals,
which includes the removal of the regular (low-frequency) components from the
source signal and the fitting of the chaotic part of the experimental
difference moment of the second order to the interpolation expression, is
presented. The procedure was applied to the analysis of the dynamics of
magnetoencephalograms, blinking fluorescence of quantum dots, and X-ray
emission from accreting objects. For all three applications, the interpolation
was able to adequately describe the chaotic part of the experimental difference
moment, which implies that anomalous diffusion manifests itself in these
natural signals. The results of this study make it possible to broaden the
range of complex natural processes in which anomalous diffusion can be
identified. The relation between the interpolation expression and a diffusion
model, which is derived in the paper, allows one to simulate the chaotic
processes in the open complex systems with anomalous diffusion.Comment: 47 pages, 15 figures; Submitted to Physical Review
Features of Polymeric Structures By Surface—Selective Laser Sintering of Polymer Particles Using Water as Sensitizer
The development of scaffolds with strictly specific properties is a key aspect of functional tissue regeneration, and it still remains one of the greatest challenges for tissue engineering. This study is aimed to determine the possibility of producing three-dimensional polylactide (PLA) scaffolds using the method of surface-selectiv laser sintering (SSLS) for bone tissue regeneration. In this work, the authors also improved PLA scaffold adhesion properties, which are crucial for successful cellular growth and expansion. Thus, SSLS method proved to be effective in designing threedimensional porous scaffolds with differentiated mechanical properties.
Keywords: regenerative medicine, scaffolds, polylactide, surface – selective laser . sintering, tissue engeneering
Normality and smoothness of simple linear group compactifications
If G is a complex semisimple algebraic group, we characterize the normality
and the smoothness of its simple linear compactifications, namely those
equivariant GxG-compactifications which possess a unique closed orbit and which
arise in a projective space of the shape P(End(V)), where V is finite
dimensional rational G-module. Both the characterizations are purely
combinatorial and are expressed in terms of the highest weights of V. In
particular, we show that Sp(2r) (with r > 0) is the unique non-adjoint simple
group which admits a simple smooth compactification.Comment: v2: minor changes, final version. To appear in Math.
Regular and stochastic behavior of Parkinsonian pathological tremor signals
Regular and stochastic behavior in the time series of Parkinsonian pathological tremor velocity is studied on the basis of the statistical theory of discrete non-Markov stochastic processes and flicker-noise spectroscopy. We have developed a new method of analyzing and diagnosing Parkinson's disease (PD) by taking into consideration discreteness, fluctuations, long- and short-range correlations, regular and stochastic behavior, Markov and non-Markov effects and dynamic alternation of relaxation modes in the initial time signals. The spectrum of the statistical non-Markovity parameter reflects Markovity and non-Markovity in the initial time series of tremor. The relaxation and kinetic parameters used in the method allow us to estimate the relaxation scales of diverse scenarios of the time signals produced by the patient in various dynamic states. The local time behavior of the initial time correlation function and the first point of the non-Markovity parameter give detailed information about the variation of pathological tremor in the local regions of the time series. The obtained results can be used to find the most effective method of reducing or suppressing pathological tremor in each individual case of a PD patient. Generally, the method allows one to assess the efficacy of the medical treatment for a group of PD patients. © 2006 Elsevier B.V. All rights reserved
The effect of the laser-induced structures’ surface morphology on the luminescence of thermostable polybenzimidazoles
This study was performed in the framework of the RFBR grant Mol_а 18-33-00645
Affine T-varieties of complexity one and locally nilpotent derivations
Let X=spec A be a normal affine variety over an algebraically closed field k
of characteristic 0 endowed with an effective action of a torus T of dimension
n. Let also D be a homogeneous locally nilpotent derivation on the normal
affine Z^n-graded domain A, so that D generates a k_+-action on X that is
normalized by the T-action. We provide a complete classification of pairs (X,D)
in two cases: for toric varieties (n=\dim X) and in the case where n=\dim X-1.
This generalizes previously known results for surfaces due to Flenner and
Zaidenberg. As an application we compute the homogeneous Makar-Limanov
invariant of such varieties. In particular we exhibit a family of non-rational
varieties with trivial Makar-Limanov invariant.Comment: 31 pages. Minor changes in the structure. Fixed some typo
Nanodiagnostics connective tissue using PF QNM technique of atomic force microscopy
Проводилось исследование биологических образцов, а именно срезов соединительной ткани: хрящ и голосовые складки. Изучалось различие строений нормальной и повреждѐнной ткани с помощью методики PF QNM на атомном силовом микроскопе.A study was conducted of biological samples, namely sections of connective tissue: cartilage and vocal cords. We studied the difference in structures of normal and defective tissue using the method PF QNM atomic force microscope
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