323 research outputs found
Calculation of the magnetic field in the active zone of a hysteresis clutch
The initial distribution of magnetic induction in the armature stationary was calculated relative to the polar system of a hysteresis clutch. Using several assumptions, the problem is reduced to calculating the static magnetic field in the ferromagnetic plate with finite and continuous magnetic permeability placed in the air gap between two identical, parallel semiconductors with rack fixed relative to the tooth or slot position
Observation of Stochastic Resonance in Percolative Josephson Media
Measurements of the electrical response of granular Sn-Ge thin films below
the superconducting transition temperature are reported. The addition of an
external noise to the magnetic field applied to the sample is found to increase
the sample voltage response to a small externally applied ac signal. The gain
coefficient for this signal and the signal-to-noise ratio display clear maxima
at particular noise levels. We interpret these observations as a stochastic
resonance in the percolative Josephson media which occurs close to the
percolation threshold.Comment: 4 pages, 5 figure
Vibronic interaction in crystals with the Jahn-Teller centers in the elementary energy bands concept
The order-disorder type phase transition caused by the vibronic interaction
(collective Jahn-Teller effect) in a monoclinic CuInPS crystal is
analyzed. For this purpose, a trigonal protostructure model of CuInPS
is created, through a slight change in the crystal lattice parameters of the
CuInPS paraelectric phase. In parallel to the group-theoretical
analysis, the DFT-based {\it ab initio} band structure calculations of the
CuInPS protostructure, para-, and ferriphases are performed. Using the
elementary energy bands concept, a part of the band structure from the vicinity
of the forbidden energy gap, which is created by the -electron states of
copper, has been related with a certain Wyckoff position where the
Jahn-Teller's centers are localized. A construction procedure of the vibronic
potential energy matrix is generalized for the case of crystal using the
elementary energy bands concept and the group theoretical method of invariants.
The procedure is illustrated by the creation of the adiabatic potentials of the
- vibronic coupling for the protostructure and paraphase of
the CuInPS crystal. A structure of the obtained adiabatic potentials is
analyzed, followed by conclusions on their transformation under a phase
transition and the discussion on the possibility for the spontaneous
polarization to arise in this crystal.Comment: 17 pages, 7 figure
A Relation Between the Flow Density and Flame Length in the Work Space of the Bath Smelting Furnace
The article provides mathematical modelling results of radiation flow formation in the work space of the smelting (glassmaking, open-hearth) furnace with different heating patterns and flow distribution over the surface of the bath and enclosing structures. A significant influence of the flame length upon technical and economic parameters of furnace operation was found out.
Keywords: bath smelting furnace, glass-melting furnace, mathematical modelling, flame length, radiation flows, temperature fiel
Особенности строения биомедицинских сплавов Ti-Nb, полученных электродуговой плавкой и селективным лазерным сплавлением
Выявлено, что при электродуговой плавке и селективном лазерном сплавлении в сплаве Ti-Nb имеет место ликвация компонентов. На участках, обогащенных Nb образуется [beta]-фаза, на участках, обедненных Nb - [alpha]''-фаза. Для устранения неоднородности фазового и элементного состава рекомендуется повысить содержание Nb в сплаве до 45 мас. %
8Li+alpha decay of 12B and its possible astrophysical implications
The 12B excitation energy spectrum has been obtained from coincidence
measurements of the 9Be+7Li -> 2alpha+8Li reaction at E{0}=52 MeV.
The decay of the states at excitations between 10 and 16 Mev into alpha$+8Li
has been observed for the first time. Observed alpha-decay indicates possible
cluster structure of the 12B excited states.
The influence of these states on the cross section of the astrophysically
important 8Li(alpha,n)11B and 9Be+t reactions is discussed and the results are
compared with existing results.Comment: accepted for publication in Europhysics Letter
Ursodeoxycholic acid prevents ventricular conduction slowing and arrhythmia by restoring T-type calcium current in fetuses during cholestasis
Background Increased maternal serum bile acid concentrations in intrahepatic cholestasis of pregnancy (ICP) are associated with fetal cardiac arrhythmias. Ursodeoxycholic acid (UDCA) has been shown to demonstrate anti-arrhythmic properties via preventing ICP-associated cardiac conduction slowing and development of reentrant arrhythmias, although the cellular mechanism is still being elucidated. Methods High-resolution fluorescent optical mapping of electrical activity and electrocardiogram measurements were used to characterize effects of UDCA on one-day-old neonatal and adult female Langendorff-perfused rat hearts. ICP was modelled by perfusion of taurocholic acid (TC, 400μM). Whole-cell calcium currents were recorded from neonatal rat and human fetal cardiomyocytes. Results TC significantly prolonged the PR interval by 11.0±3.5% (P<0.05) and slowed ventricular conduction velocity (CV) by 38.9±5.1% (P<0.05) exclusively in neonatal and not in maternal hearts. A similar CV decline was observed with the selective T-type calcium current (ICa,T) blocker mibefradil 1μM (23.0±6.2%, P<0.05), but not with the L-type calcium current (ICa,L) blocker nifedipine 1μM (6.9±6.6%, NS). The sodium channel blocker lidocaine (30μM) reduced CV by 60.4±4.5% (P<0.05). UDCA co-treatment was protective against CV slowing induced by TC and mibefradil, but not against lidocaine. UDCA prevented the TC-induced reduction in the ICa,T density in both isolated human fetal (−10.2±1.5 versus −5.5±0.9 pA/pF, P<0.05) and neonatal rat ventricular myocytes (−22.3±1.1 versus −9.6±0.8 pA/pF, P<0.0001), whereas UDCA had limited efficacy on the ICa,L. Conclusion Our findings demonstrate that ICa,T plays a significant role in ICP-associated fetal cardiac conduction slowing and arrhythmogenesis, and is an important component of the fetus-specific anti-arrhythmic activity of UDCA
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