541 research outputs found
Classification of Cohomogeneity One Strings
We define the cohomogeneity one string, string with continuous symmetries, as
its world surface is tangent to a Killing vector field of a target space. We
classify the Killing vector fields by an equivalence relation using isometries
of the target space. We find that the equivalence classes of Killing vectors in
Minkowski spacetime are partitioned into seven families. It is clarified that
there exist seven types of strings with spacelike symmetries and four types of
strings with timelike symmetries, stationary strings.Comment: 8 page
Families of Roles: A new theory of occurrent-dependent roles
PublishedRoles are important both theoretically and practically for modelling the world around us. Although many theories of roles have been proposed, there remain aspects which are little understood. In this paper we investigate roles and their contexts from a temporal point of view.We introduce the idea of a family of occurrent-dependent roles as a means to organise prospective and retrospective derived roles around an original role from which they are derived. By this means we account for the existence of groups of similar roles which are difficult to distinguish without a careful analysis of the temporal aspects. Following detailed informal discussion, we present a preliminary formalisation of the key concepts and relations.Air Force Research Laborator
Aperiodic nano-photonic design
The photon scattering properties of aperiodic nano-scale dielectric
structures can be tailored to closely match a desired response by using
adaptive algorithms for device design. We show that broken symmetry of
aperiodic designs provides access to device functions not available to
conventional periodic photonic crystal structures.Comment: 23 pages, LaTex, 8 postscript figure
Stationary Rotating Strings as Relativistic Particle Mechanics
Stationary rotating strings can be viewed as geodesic motions in appropriate
metrics on a two-dimensional space. We obtain all solutions describing
stationary rotating strings in flat spacetime as an application. These rotating
strings have infinite length with various wiggly shapes. Averaged value of the
string energy, the angular momentum and the linear momentum along the string
are discussed.Comment: 20pages, 7 figure
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