1,059 research outputs found
Main mechanisms and features of epileptogenesis of post-traumatic epilepsy
One of the most frequent and formidable consequences of traumatic brain injury (TBI) is post-traumatic epilepsy (PTE), which is the main identified cause of symptomatic epilepsy at a young age.The work highlights the "trigger" mechanisms of brain damage, including oxidative stress, leading to the disintegration of all levels of the central nervous system, contributing to the development of neuropathological syndromes, and especially PTE.The questions of differentiation of PTE from other epileptic paroxysms, the dependence of the development of PTE on the severity of TBI, the main risk factors for this type of epileptogenesis, its phasing, as well as disorganization and damage to the antiepileptic system are considered. The place of a nonspecific response to damage in the form of immediate and early seizures, their metamorphosis as the formation of PTE was determined.The existing spectrum of convulsive seizures is described, including partial, taking into account the localization characteristic of TBI with a predominance of lezional forms
Influence of magnesium on excitability of neurons of different levels of their organization
AbstractThe article indicates that the hyper-excitability of neurons is associated with ionic imbalance of cell membranes, in which a number of trace elements are involved. The energy component of these processes is associated with the presence of magnesium (Mg) as a universal supplier of the latter. Mg supports the functioning of NMDA receptors, which does not allow the excitotoxic effects of glutamate, which triggers the mechanisms of Ca entry into the neuron and its death, to manifest itself. Mg stimulates the main excitatory neurotransmitter acetylcholine, regulates the release of serotonin, glycine, dopamine, thereby normalizing the extrapyramidal system, the spinal stem structures, and the final executive motor apparatus. Participates in the energy support of adaptation processes, the activation of central regulatory mechanisms, control the excess of catecholamines and corticosteroids, other hormones and mediators involved in stress reactions
Critical exponents for 3D O(n)-symmetric model with n > 3
Critical exponents for the 3D O(n)-symmetric model with n > 3 are estimated
on the base of six-loop renormalization-group (RG) expansions. A simple
Pade-Borel technique is used for the resummation of the RG series and the Pade
approximants [L/1] are shown to give rather good numerical results for all
calculated quantities. For large n, the fixed point location g_c and the
critical exponents are also determined directly from six-loop expansions
without addressing the resummation procedure. An analysis of the numbers
obtained shows that resummation becomes unnecessary when n exceeds 28 provided
an accuracy of about 0.01 is adopted as satisfactory for g_c and critical
exponents. Further, results of the calculations performed are used to estimate
the numerical accuracy of the 1/n-expansion. The same value n = 28 is shown to
play the role of the lower boundary of the domain where this approximation
provides high-precision estimates for the critical exponents.Comment: 10 pages, TeX, no figure
Critical behavior of frustrated systems: Monte Carlo simulations versus Renormalization Group
We study the critical behavior of frustrated systems by means of Pade-Borel
resummed three-loop renormalization-group expansions and numerical Monte Carlo
simulations. Amazingly, for six-component spins where the transition is second
order, both approaches disagree. This unusual situation is analyzed both from
the point of view of the convergence of the resummed series and from the
possible relevance of non perturbative effects.Comment: RevTex, 10 pages, 3 Postscript figure
Critical behavior of three-dimensional magnets with complicated ordering from three-loop renormalization-group expansions
The critical behavior of a model describing phase transitions in 3D
antiferromagnets with 2N-component real order parameters is studied within the
renormalization-group (RG) approach. The RG functions are calculated in the
three-loop order and resummed by the generalized Pade-Borel procedure
preserving the specific symmetry properties of the model. An anisotropic stable
fixed point is found to exist in the RG flow diagram for N > 1 and lies near
the Bose fixed point; corresponding critical exponents are close to those of
the XY model. The accuracy of the results obtained is discussed and estimated.Comment: 10 pages, LaTeX, revised version published in Phys. Rev.
Features and Cost Comparison of Biologically Inspired Vision Systems
The economic analysis of the advantages of known analogues of biologically inspired systems for
unmanned aerial vehicles (UAVs), quadrocopters, etc
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