Azimuthal surface waves in a coaxial semiconductor structure with metal walls

The dispersion properties and topography of the fields of azimuthal surface wave (ASW) in a coaxial semiconductor structure with metal walls, placed in an external magnetic field, are investigated analytically and numerically. It is shown that an ASW phase-shifting device can be realized in the proposed structure. The conditions are indicated for which wave perturbations exist having frequencies that depend on the direction of phase change.

Dispersion characteristics of a cylindrical antenna in magnetoactive plasma

Dispersion characteristics and topography of electromagnetic fields of axially symmetric surface waves (SW) and of azimuth surface waves (ASW) propagating in a structure composed of a cylindrical metal antenna and magnetoactive plasma are investigated. The antenna and plasma may be separated by a vacuum layer. The dispersion characteristics of SW and ASW are presented as functions of the antenna and the magnetoactive plasma parameters. Close agreement between theory and experimental results are shown. Surface impedances of the SW and ASW are calculated for various parameters of the problem.

Nonlinear interactions of azimuthal surface waves in magnetoactive plasma filled waveguides

This paper deals with the theoretical studies of nonlinear interactions of azimuthal surface waves (ASW) in cylindrical metal waveguides fully filled by a uniform magnetoactive plasma. These surface-type wave perturbations propagate in azimuthal direction across an external magnetic field, which is directed along the waveguide axis. The ASW is a relatively new kind of surface waves and so far the nonlinear effects associated with their propagation are outside the scope of scientific issues. They are characterized by a discrete set of mode numbers values which define the ASW eigenfrequencies. This fact leads to several peculiarities of ASW compared with ordinary surface-type waves.

Reflexive writers : re-thinking writing development and assessment in schools

Writing is a complex and highly individual activity, which is approached in different ways by different writers. Writers reflexively mediate subjective and objective conditions in specific and nuanced ways to produce a product in time and place. This paper uses a critical realist theory of reflexivity to argue that the teaching and assessment of writing must account for the different ways that students manage and make decisions in their writing. Data from linguistically and culturally diverse primary students in Australia are used to illustrate how four distinct reflexive modalities constitute the ways in which students approach writing. The paper offers a new approach to assessing writing for and of learning that considers writers as reflexive and agentic in different ways. It posits the importance of making visible and explicit the context and reflexive decision-making as writers shape a product for a purpose and audience.