Biomedical subjects

D B Litvin

Publications and source records attributed to D B Litvin.

7 recordsLinked to original sources

PubMed2006

Distinction of magnetic non-ferroelastic domains.

It is shown that there always exists a coordinate system in which components of property tensors that distinguish between the domains of a magnetic non-ferroelastic domain pair differ solely in the two domains by a change in sign. The 309 classes of twin laws of magnetic non-ferroelastic domain pairs are listed and the twin laws, which are given in a coordinate system where the tensor distinction is provided by a change in sign of tensor components, are specified. If the twin law is not given in such a coordinate system, then a new coordinate system, related by a rotation, is specified.

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PubMed2005

Tables of properties of magnetic subperiodic groups.

Tables of crystallographic properties of the magnetic subperiodic groups, i.e. the 31 magnetic frieze-group types, the 394 magnetic rod-group types and the 528 magnetic layer-group types are presented. The content and format is similar to that of non-magnetic subperiodic groups and space groups given in International Tables for Crystallography. Additional content for each group type includes a diagram of general positions with corresponding general magnetic moments, Seitz notation used as a second notation for symmetry operations, and general and special positions listed with the components of the corresponding magnetic moments allowed by symmetry.

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PubMed2001

Latent symmetry.

A theorem is proven which provides a sufficient condition that an isometry is a symmetry of a composite constructed from a component and a group of isometries. The concept of latent symmetry is broadened and this theorem is applied to deduce latent symmetry of example composites, including an example discussed by Litvin & Wadhawan [Acta Cryst. (2001), A57, 435-441], the latent symmetry of which could not be determined there systematically.

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PubMed2001

Magnetic space-group types.

The interpretation of Opechowski-Guccione symbols for magnetic space-group types is based on coordinate triplets given in the now superceded International Tables for X-ray Crystallography [(1952), Vol. 1, edited by N. F. M. Henry & K. Lonsdale. Birmingham: Kynoch Press]. Changes to coordinate triplets in International Tables for Crystallography [(1983), Vol. A, edited by Th. Hahn. Dordrecht: Kluwer Academic Publishers] lead to misinterpretations of these symbols. A list is provided here of Opechowski-Guccione symbols for the 1651 magnetic space-group types with their original definitions given independent of International Tables.

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PubMed2001

Symmetry relations of magnetic twin laws.

Symmetry relationships between two simultaneously observed domain states (domain pair) are used to determine physical properties that can distinguish between the observed domains. Here the tabulation of these symmetry relationships is extended from non-magnetic cases to magnetic cases, in terms of magnetic point groups, i.e. all possible magnetic symmetry groups and magnetic twinning groups of domain pairs are determined and tabulated.

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PubMed2001

Latent symmetry and its group theoretical determination.

Latent symmetry of a component of a composite object is defined as that symmetry of a subunit of the component which is not a symmetry of the component but which is a symmetry of the composite. This is illustrated by a geometrical example. A group theoretical procedure is given to determine latent symmetry and is applied to examples.

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PubMed2001

Coset and double-coset decompositions of the magnetic point groups.

The coset and double-coset decompositions of the 420 subgroups of m(z)3(xyz)m(xy)1' (O(h)1') and the 236 subgroups of 6(z)/m(z)m(x)m(1)1' (D(6h)1') with respect to each of their subgroups are calculated along with additional mathematical properties of these groups.

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