236 research outputs found
Modelling of Permanent Magnets Track in the Finite Element Analysis of Linear Synchronous Motor
The paper presents a special technique for magnetic way modeling in its FEM - based ( Finite Elements Method) analysis of the AC magnetic field, which aims at accurate calculation of forces acting on the movingnbsp part of one Permanent Magnet Linear Synchronousnbsp Motor (PMLSM). Here has been used an approximation of AC solutions of problems for linear motors with replacing the permanent magnet ways by AC current sheets.nbsp This models the synchronous movement of the magnets interacting with the AC currents in the mover winding. Calculated thrust and attractive force of the linear motor on the base of AC and DC motor magnetic field analysis was compared with the results from experiment and their good match has been proved
About the magnetic fluctuation effect on the phase transition to superconducting state in Al
The free energy and the order parameter profile near the phase transition to
the superconducting state in bulk Al samples are calculated within a
mean-field-like approximation. The results are compared with those for thin
films.Comment: 11 pages, miktex, 2 figure
ON SOME PHARMACOLOGICAL PROPERТIES OF ТНЕ ALKALOIDS OF VINCA MAJOR
Pharmacological studies of the alkaloids of Vinca minor and Vinca hеrbасеае revealed that compounds found in these plants аrе highly active pharmacologic agents. Тhеу hаve а sedative effect оn the central nervous system, they considerably lower the blооd pressure, theyblосk some ganglia, belonging to the parasympathetic part of the vegetative nervous system and interrupt the transmission of nervous impulses in the myo-neural synapses, realizing а curare-like effect; they also anesthesize the receptors of the cornea etc. On the basis of these investigations а maгket product was deliveгed under the name of Vincaipan, containing the total alkaloids of Vinca minor, whose previous clinical trial seemed quite encuoraging. All this stimulated the phytochemical and pharmacological elaboration of the third representative of the botanic family Appocynaceae. This plant also belongs to the species Vinca - Vinca major, grown in our country. Mention slhould also bе made of the fact that according to phytochemical investigations of а number of foreign authors Vinca major contains alkaloids with indolic structure, which аrе more or less structurally гelated to гeserpine, whose polypharmacological activity and great therapeutic significance аrе well known.These were the motives fог our systematic pharmaco1logical analysis of the total alkaloids of this plant. obtained at the Chair of Pharmacology at the Higher Medical Institute in Varna.
Regulation of transsynaptically elicited increase of 3':5'-cyclic AMP by endogenous phosphodiesterase activator.
Thermodynamics of ferromagnetic superconductors with spin-triplet electron pairing
We present a general thermodynamic theory that describes phases and phase
transitions of ferromagnetic superconductors with spin-triplet electron Cooper
pairing. The theory is based on extended Ginzburg-Landau expansion in powers of
superconducting and ferromagnetic order parameters. We propose a simple form
for the dependence of theory parameters on the pressure that allows correct
theoretical outline of the temperature-pressure phase diagram for which at low
temperatures a stable phase of coexistence of p-wave superconductivity and
itinerant ferromagnetism appears. We demonstrate that the theory is in an
agreement with the experimental data for some intermetallic compounds that are
experimentally proven to be itinerant ferromagnetic exhibiting spin-triplet
superconductivity. Some basic features of quantum phase transitions in such
systems are explained and clarified. We propose to group the spin-triplet
ferromagnetic superconductors in two different types of thermodynamic behavior,
on the basis of quantitative criterion deduced from the present theory and the
analysis of experimental data.Comment: Phys. Rev. B (2009) in PRESS; 14 pages, 1 table, 6 figures, Latex2
RED LIST OF BULGARIAN ALGAE. II. MICROALGAE.
The Red List presented in this paper is focused on Bulgarian non-marine microalgae which face a risk of extinction. The assignment to each IUCN Red List category is according to the seven specific criteria and their relative values in the new method for an evaluation of the threatened status of microalgae (STOYNEVA-GÄRTNER ET AL., this volume). The list contains 756 taxa (613 species, 82 varieties and 61 forms) from 7 divisions, classified in six IUCN categories and shows that threatened microalgae represent 14% the total algal biodiversity of Bulgaria
New features of the phase transition to superconducting state in thin films
The Halperin-Lubensky-Ma (HLM) effect of a fluctuation-induced change of the
order of phase transition in thin films of type I superconductors with
relatively small Ginzburg-Landau number is considered. Numerical data
for the free energy, the order parameter jump, the latent heat, and the
specific heat of W, Al and In are presented to reveal the influence of film
thickness and material parameters on the properties of the phase transition. We
demonstrate for the first time that in contrast to the usual notion the HLM
effect occurs in the most distinct way in superconducting films with high
critical magnetic field rather than in materials with small .
The possibility for an experimental observation of the fluctuation change of
the order of superconducting phase transition in superconducting films is
discussed.Comment: 11 pages, MikTexTeX, 3 fig, 2 Tables, corrected some typos, Submitted
J.Phys:Cond Ma
REVIEW OF THE CURRENT STATUS AND FUTURE PERSPECTIVES ON PSEUDOGYMNOASCUS DESTRUCTANS STUDIES WITH REFERENCE TO SPECIES FINDINGS IN BULGARIA
Emerging infectious diseases are a well-known threat to the wildlife and require complex research. There is a rapidly accumulating knowledge on the infectious disease of bats, named firstly White Nose Syndrome (WNS) and afterwards – White Nose Disease (WND), and its causative agent – the pathogenic fungus Pseudogymnoascus destructans. Although mass mortality of bats, known since a decade, is currently restricted to North America, the pathogen is of global concern as a potential threat to other hibernating bat populations. Therefore five years after the first comprehensive synthesis on the fungal ecology and relevant knowledge gaps (FOLEY ET AL. 2011), we decided to summarize the published information on the pathogen morphology, reproduction, ecological requirements, geographic distribution and systematic position. In addition, the present review compiles the available data on the affected bat species, mechanisms of WND, on the host response and on the effective treatment strategies with possible methods for fighting the pathogen to reduce the mortality in affected regions as well. Special attention is paid to the finding of the fungus in Bulgarian caves
Dynamical properties of the Landau-Ginzburg model with long-range correlated quenched impurities
We investigate the critical dynamics of the time-dependent Landau-Ginzburg
model with non conserved n-component order parameter (Model A) in the presence
of long-range correlated quenched impurities. We use a special kind of
long-range correlations, previously introduced by Weinrib and Halperin. Using a
double expansion in \epsilon and \delta we calculate the critical exponent z up
to second order on the small parameters. We show that the quenched impurities
of this kind affect the critical dynamics already in first order of \epsilon
and \delta, leading to a relevant correction for the mean field value of the
exponent zComment: 7 pages, REVTEX, to be published in Phys. Rev.
Studies on cyanoprokaryotes of the water bodies along the Bulgarian Black Sea Coast (1890-2017):A review, with special reference to new, rare and harmful taxa
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