1,827 research outputs found
Spatial Imperfection Encodes Functional Perfection: Success and Failure of Calcium Release to Propagate Regulate Pacemaker Cell Function
Congruence modularity implies cyclic terms for finite algebras
An n-ary operation f : A(n) -> A is called cyclic if it is idempotent and f(a(1), a(2), a(3), ... , a(n)) = f(a(2), a(3), ... , a(n), a(1)) for every a(1), ... , a(n) is an element of A. We prove that every finite algebra A in a congruence modular variety has a p-ary cyclic term operation for any prime p greater than vertical bar A vertical bar
Lanthanum Activity in La–U–Ga–X Systems (X = Al or In)
Lanthanum activity was determined for the first time in La–U–Ga–X (X = Al or In) alloys. Ga–In and Ga–Al alloys were taken in the eutectic composition (21.8 wt.% In and 1.6 wt.% Al, respectively). Measurements were performed between 573 and 1073 K employing the e.m.f. method.
Keywords: Lanthanum; Uranium; Gallium-Indium Eutectic; Gallium-Aluminium Eutectic; Activity; Thermodynamics
Multi-Lagrangians, Hereditary Operators and Lax Pairs for the Korteweg-de Vries Positive and Negative Hierarchies
We present an approach to the construction of action principles for
differential equations, and apply it to field theory in order to construct
systematically, for integrable equations which are based on a Nijenhuis (or
hereditary) operator, a ladder of action principles which is complementary to
the well-known multi-Hamiltonian formulation. We work out results for the
Korteweg-de Vries (KdV) equation, which is a member of the positive hierarchy
related to a hereditary operator. Three negative hierarchies of (negative)
evolution equations are defined naturally from the hereditary operator as well,
in the context of field theory. The Euler-Lagrange equations arising from the
action principles are equivalent to the original evolution equation +
deformations, which are obtained in terms of the positive and negative
evolution vectors. We recognize the Liouville, Sinh-Gordon, Hunter-Zheng and
Camassa-Holm equations as negative equations. The ladder for KdV is directly
mappable to a ladder for any of these negative equations and other positive
equations (e.g., the Harry-Dym and a special case of the Krichever-Novikov
equations): a new nonlocal action principle for the deformed system Sinh-Gordon
+ spatial translation vector is presented. Several nonequivalent, nonlocal
time-reparametrization invariant action principles for KdV are constructed.
Hamiltonian and Symplectic operators are obtained in factorized form.
Alternative Lax pairs for all negative flows are constructed, using the flows
and the hereditary operator as only input. From this result we prove that all
positive and negative equations in the hierarchies share the same sets of local
and nonlocal constants of the motion for KdV, which are explicitly obtained
using the local and nonlocal action principles for KdV.Comment: Final version, accepted in JMP; RevTeX, 31 page
Relativistic Stark energies of hydrogen-like ions
The relativistic energies and widths of hydrogen-like ions exposed to the
uniform electric field are calculated. The calculations are performed for the
ground and lowest excited states using the complex scaling technique in
combination with a finite-basis method. The obtained results are compared with
the non-relativistic values. The role of relativistic effects is investigated.Comment: 21 pages, 5 figure
Model of ionic currents through microtubule nanopores and the lumen
It has been suggested that microtubules and other cytoskeletal filaments may
act as electrical transmission lines. An electrical circuit model of the
microtubule is constructed incorporating features of its cylindrical structure
with nanopores in its walls. This model is used to study how ionic conductance
along the lumen is affected by flux through the nanopores when an external
potential is applied across its two ends. Based on the results of Brownian
dynamics simulations, the nanopores were found to have asymmetric inner and
outer conductances, manifested as nonlinear IV curves. Our simulations indicate
that a combination of this asymmetry and an internal voltage source arising
from the motion of the C-terminal tails causes a net current to be pumped
across the microtubule wall and propagate down the microtubule through the
lumen. This effect is demonstrated to enhance and add directly to the
longitudinal current through the lumen resulting from an external voltage
source, and could be significant in amplifying low-intensity endogenous
currents within the cellular environment or as a nano-bioelectronic device.Comment: 43 pages, 6 figures, revised versio
The effect of fission product elements on the behavior of uranyl species in alkali chloride melts: A contribution towards reprocessing spent oxide fuels
The reactions of uranyl(VI) containing chloride melts with molybdenum, niobium, zirconium and palladium were studied using high temperature electronic absorption spectroscopy. Depending on the nature of the added element uranium is reduced to uranyl(V) and uranium(IV) chloro-species and UO2. Palladium, niobium and zirconium can all be removed from a uranyl(VI)-containing melt using molybdenum metal and the melt can then be purified from Mo(III) ions by bubbling Cl2 gas. Such approach can be employed for removal a number of fission product elements from molten chloride baths during reprocessing spent oxide fuels. ©The Electrochemical Society.Physical and Analytical Electrochemistry;Electrodeposition;Energy Technolog
Spontaneous vacuum decay in low-energy collisions of heavy nuclei beyond the monopole approximation
The problem of spontaneous vacuum decay in low-energy collisions of heavy
nuclei is considered beyond the scope of the monopole approximation. The
time-dependent Dirac equation is solved in a rotating coordinate system with
-axis directed along the internuclear line and the origin placed at the
center of mass. The probabilities of electron-positron pair creation and the
positron energy spectra are calculated in the approximation neglecting the
rotational coupling. The two-center potential is expanded over spherical
harmonics and the convergence with respect to the number of terms in this
expansion is studied. The results show that taking into account the two-center
potential instead of its spherically symmetric part preserves all the
signatures of the transition to the supercritical regime that have been found
in the framework of the monopole approximation and even enhances some of them.Comment: 7 pages, 4 figures, 1 tabl
Structure and Phase Composition of Zirconium Fuel Claddings in Initial State and after Creep Tests
The article's abstract is no available
Quasiperiodic functions theory and the superlattice potentials for a two-dimensional electron gas
We consider Novikov problem of the classification of level curves of
quasiperiodic functions on the plane and its connection with the conductivity
of two-dimensional electron gas in the presence of both orthogonal magnetic
field and the superlattice potentials of special type. We show that the
modulation techniques used in the recent papers on the 2D heterostructures
permit to obtain the general quasiperiodic potentials for 2D electron gas and
consider the asymptotic limit of conductivity when . Using the
theory of quasiperiodic functions we introduce here the topological
characteristics of such potentials observable in the conductivity. The
corresponding characteristics are the direct analog of the "topological
numbers" introduced previously in the conductivity of normal metals.Comment: Revtex, 16 pages, 12 figure
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