228 research outputs found
Implicit Euler scheme for an abstract evolution inequality
For a triple {V, H, V*} of Hilbert spaces, we consider an evolution inclusion of the form u′(t)+A(t)u(t)+δφ{symbol}(t, u(t)) ∋f(t), u(0) = u0, t ∈ (0, T ], where A(t) and φ{symbol}(t, ·), t ∈ [0, T], are a family of nonlinear operators from V to V * and a family of convex lower semicontinuous functionals with common effective domain D(φ{symbol}) ⊂ V. We indicate conditions on the data under which there exists a unique solution of the problem in the space H1(0, T; V)∩W∞ 1 (0, T;H) and the implicit Euler method has first-order accuracy in the energy norm. © 2011 Pleiades Publishing, Ltd
Exact penalty operators and regularization of parabolic variational inequalities with an obstacle inside a domain
A class of parabolic variational inequalities with zero obstacle inside the domain is considered. For this class, exact penalty operators are defined, which are then used to construct and study regularization methods. The following estimates are obtained for the closeness of the original and regularized problem: u - ε1 ≤uε + ε1 and ∥u-uε ∥ L2(0,T;V0) = O(ε3/4). © 2008 MAIK Nauka
Accuracy of discrete schemes for a class of abstract evolution inequalities
For a triple of Hilbert spaces {V, H, V*}, we study a discrete and a semidiscrete scheme for an evolution inclusion of the form u′(t) + A(t)u(t) + ∂φ{symbol}(t, u(t)) ∋ f(t), u(0) = u 0, t ∈ (0, T], where the pair {A(t), φ{symbol}(t, ·)} consists of a family of nonlinear operators from V into V* and a family of proper convex lower semicontinuous functionals with common effective domain D(φ{symbol}) ⊂ V. The discrete scheme is a combination of the Galerkin method with perturbations and the implicit Euler method. Under conditions on the data providing the existence and uniqueness of the solution of the problem in the space H1(0, T; V) ∩ W∞ 1(0, T;H), we obtain an abstract estimate for the method error in the energy norm of first-order accuracy with respect to the time increment. By way of application, we consider a problem with an obstacle inside the domain, for which we obtain an optimal estimate of the accuracy of two implicit schemes (standard and new) on the basis of the finite element method. © 2013 Pleiades Publishing, Ltd
Stability of the coincidence set of a solution to a parabolic variational inequality with an obstacle
In this paper we propose a new technique for the stability analysis of the coincidence set of a solution to a parabolic variational inequality with an obstacle inside the domain. It is based on the reformulation of the initial inequality in the form of a parabolic initial boundary value problem with an exact penalty operator. © 2010 Allerton Press, Inc
Role of Nitric Oxide Produced by Lactobacilli in Relaxation of Intestinal Smooth Muscles
© 2016, Springer Science+Business Media New York.Application of NO-producing lactobacilli to a rat jejunum segment induced muscle relaxation that was potentiated after activation of bacterial NO production with NO synthase substrate L-arginine. Similar changes in the intestinal contractile activity were observed in response to exogenous NO formed by sodium nitroprusside. These results indicated the involvement of NO synthesized by probiotic lactobacilli in the regulation of the intestinal motor function
Role of Nitric Oxide Produced by Lactobacilli in Relaxation of Intestinal Smooth Muscles
© 2016 Springer Science+Business Media New York Application of NO-producing lactobacilli to a rat jejunum segment induced muscle relaxation that was potentiated after activation of bacterial NO production with NO synthase substrate L-arginine. Similar changes in the intestinal contractile activity were observed in response to exogenous NO formed by sodium nitroprusside. These results indicated the involvement of NO synthesized by probiotic lactobacilli in the regulation of the intestinal motor function
Role of Nitric Oxide Produced by Lactobacilli in Relaxation of Intestinal Smooth Muscles
© 2016, Springer Science+Business Media New York.Application of NO-producing lactobacilli to a rat jejunum segment induced muscle relaxation that was potentiated after activation of bacterial NO production with NO synthase substrate L-arginine. Similar changes in the intestinal contractile activity were observed in response to exogenous NO formed by sodium nitroprusside. These results indicated the involvement of NO synthesized by probiotic lactobacilli in the regulation of the intestinal motor function
On creating mass/matter by extra dimensions in the Einstein-Gauss-Bonnet gravity
Kaluza-Klein (KK) black hole solutions in the Einstein-Gauss-Bonnet (EGB)
gravity in dimensions obtained in the current series of the works by Maeda,
Dadhich and Molina are examined. Interpreting their solutions, the authors
claim that the mass/matter is created by the extra dimensions. To support this
claim, one needs to show that such objects have classically defined masses. We
calculate the mass and mass flux for 3D KK black holes in 6D EGB gravity whose
properties are sufficiently physically interesting. Superpotentials for
arbitrary types of perturbations on arbitrary curved backgrounds, recently
obtained by the author, are used, and acceptable mass and mass flux are
obtained. A possibility of considering the KK created matter as dark matter in
the Universe is discussed.Comment: 15 pages, no figures, minor changes related to the Journal
publication with adding two references in footnote
Observational Manifestations of the First Protogalaxies in the 21 cm Line
The absorption properties of the first low-mass protogalaxies (mini-halos)
forming at high redshifts in the 21-cm line of atomic hydrogen are considered.
The absorption properties of these protogalaxies are shown to depend strongly
on both their mass and evolutionary status. The optical depths in the line
reach 0.1-0.2 for small impact parameters of the line of sight. When a
protogalaxy being compressed, the influence of gas accretion can be seen
manifested in a non-monotonic frequency dependence of the optical depth. The
absorption characteristics in the 21-cm line are determined by the thermal and
dynamical evolution of the gas in protogalaxies. Since the theoretical line
width in the observer's reference frame is 1-6 kHz and the expected separation
between lines 8.4 kHz, the lines from low mass protogalaxies can be resolved
using ongoing and future low frequency interferometers.Comment: 12 pages, 5 figure
The Quantum Propagator for a Nonrelativistic Particle in the Vicinity of a Time Machine
We study the propagator of a non-relativistic, non-interacting particle in
any non-relativistic ``time-machine'' spacetime of the type shown in Fig.~1: an
external, flat spacetime in which two spatial regions, at time and
at time , are connected by two temporal wormholes, one leading from
the past side of to t the future side of and the other from the
past side of to the future side of . We express the propagator
explicitly in terms of those for ordinary, flat spacetime and for the two
wormholes; and from that expression we show that the propagator satisfies
completeness and unitarity in the initial and final ``chronal regions''
(regions without closed timelike curves) and its propagation from the initial
region to the final region is unitary. However, within the time machine it
satisfies neither completeness nor unitarity. We also give an alternative proof
of initial-region-to-final-region unitarity based on a conserved current and
Gauss's theorem. This proof can be carried over without change to most any
non-relativistic time-machine spacetime; it is the non-relativistic version of
a theorem by Friedman, Papastamatiou and Simon, which says that for a free
scalar field, quantum mechanical unitarity follows from the fact that the
classical evolution preserves the Klein-Gordon inner product
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