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Fixed Domain (fixed + domain)

Distribution by Scientific Domains
Mathematics and Statistics40%

Selected Abstracts

Homogenization of elliptic problems with the Dirichlet and Neumann conditions imposed on varying subsets

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 14 2007
Carmen Calvo-Jurado
Abstract We study the asymptotic behaviour of the solution un of a linear elliptic equation posed in a fixed domain ,. The solution un is assumed to satisfy a Dirichlet boundary condition on ,n, where ,n is an arbitrary sequence of subsets of ,,, and a Neumman boundary condition on the remainder of ,,. We obtain a representation of the limit problem which is stable by homogenization and where it appears a generalized Fourier boundary condition. We also prove a corrector result. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Numerical simulation of non-viscous liquid pinch off using a coupled level set boundary integral method

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2007
Maria Garzon
The pinch off of an inviscid fluid column is described using a potential flow model with capillary forces. The interface velocity is obtained via a Galerkin boundary integral method for the 3D axisymmetric Laplace equation, whereas the interface location and the velocity potential on the free boundary are both approximated using level set techniques on a fixed domain. The algorithm is validated computing the Raleigh-Taylor instability for liquid columns which provides an analytical solution for short times. The simulations show the time evolution of the fluid tube and the algorithm is capable of handling pinch-off and after pinch-off events. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Induced fit in guanidino kinases,comparison of substrate-free and transition state analog structures of arginine kinase

PROTEIN SCIENCE, Issue 1 2003
Mohammad S. Yousef
Abstract Arginine kinase (AK) is a member of the guanidino kinase family that plays an important role in buffering ATP concentration in cells with high and fluctuating energy demands. The AK specifically catalyzes the reversible phosphoryl transfer between ATP and arginine. We have determined the crystal structure of AK from the horseshoe crab (Limulus polyphemus) in its open (substrate-free) form. The final model has been refined at 2.35 Å with a final R of 22.3% (Rfree = 23.7%). The structure of the open form is compared to the previously determined structure of the transition state analog complex in the closed form. Classically, the protein would be considered two domain, but dynamic domain (DynDom) analysis shows that most of the differences between the two structures can be considered as the motion between four rigid groups of nonsequential residues. ATP binds near a cluster of positively charged residues of a fixed dynamic domain. The other three dynamic domains close the active site with separate hinge rotations relative to the fixed domain. Several residues of key importance for the induced motion are conserved within the phosphagen kinase family, including creatine kinase. Substantial conformational changes are induced in different parts of the enzyme as intimate interactions are formed with both substrates. Thus, although induced fit occurs in a number of phosphoryl transfer enzymes, the conformational changes in phosphagen kinases appear to be more complicated than in prior examples. [source]

Local existence for the free boundary problem for nonrelativistic and Relativistic compressible Euler equations with a vacuum boundary condition

COMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 11 2009
Yuri Trakhinin
We study the free boundary problem for the equations of compressible Euler equations with a vacuum boundary condition. Our main goal is to recover in Eulerian coordinates the earlier well-posedness result obtained by Lindblad [11] for the isentropic Euler equations and extend it to the case of full gas dynamics. For technical simplicity we consider the case of an unbounded domain whose boundary has the form of a graph and make short comments about the case of a bounded domain. We prove the local-in-time existence in Sobolev spaces by the technique applied earlier to weakly stable shock waves and characteristic discontinuities [5, 12]. It contains, in particular, the reduction to a fixed domain, using the "good unknown" of Alinhac [1], and a suitable Nash-Moser-type iteration scheme. A certain modification of such an approach is caused by the fact that the symbol associated to the free surface is not elliptic. This approach is still directly applicable to the relativistic version of our problem in the setting of special relativity, and we briefly discuss its extension to general relativity. © 2009 Wiley Periodicals, Inc. [source]

Morphology of phase-separated thermotropic layers based on UV cured acrylate resins

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2009
Katharina Resch
Abstract In this paper, relationships between the scattering domain parameters (size and shape) and the light-shielding properties of thermotropic systems with fixed domains (TSFD) are established. Specific focus is given to the effect of additive type on the formation of scattering domain size. Various functional layers are prepared by a variation of thermotropic additives. Scattering domains are investigated applying high resolution Atomic Force Microscopy (AFM) in a phase imaging mode. Thermotropic layers formulated with additive types exhibiting a short chain length display roughly spherical scattering particles with dimensions between 0.5 and 3,µm and a moderate reduction in hemispheric solar transmittance along with a significant increase in diffuse solar transmittance above the switching threshold. Additive types with long-chain molecules develop anisotropic scattering domains resembling distorted disks with a diameter up to 50,µm and a thickness between 100 and 400,nm. Disk-like scattering features yield enhanced light-shielding properties. Copyright © 2009 John Wiley & Sons, Ltd. [source]