Extreme ultraviolet emission lines of Ni xii in laboratory and solar spectra

A linear force-free field solution is presented in cylindrical coordinates, formulated in terms of trigonometric and Bessel functions. A numerical exploration has revealed that this solution describes magnetic field lines that meander in Cartesian space, as well as field lines that lie on toroidal flux surfaces. These tori are in (or close to) the plane perpendicular to the cylindrical axis. Nested tori, as well as tori with shells that have finite thickness, were found. The parameter space of the solution shows that the tori exist within a bounded range of values

A new family of solutions of the force-free field equation

A new family of solutions has been found for force-free magnetic fields and Beltrami flows, which admits a complete classification in terms of the eigenvalues of the problem. In the absence of boundary values to determine them uniquely, the eigenvalues correspond to the entire set of real numbers, except for zero. The eigenvalues are degenerate in that each eigenvalue has many eigensolutions associated with it. For each eigensolution we have been able to identify sets of equilibrium or null points and lines. The linear mappings of these null points and lines are all unstable. Finally, we derive the first integral of energy associated with this family of solutions

Lexicographic training at the Bureau of the Woordeboek van die Afrikaanse taal

Since 1995, the Bureau of the WAT has developed several training courses for students and other persons interested in gaining insight into and practical experience of the planning, compilation and management of a dictionary. This article summarizes the courses offered. Keywords: general lexicography, computer lexicography, co-operative training, dictionary typology, dictionary planning, dictionary compilation, dictionary managemen

The structure of force-free magnetic fields

Incontrovertible evidence is presented that the force-free magnetic fields exhibit strong stochastic behavior. Arnold’s solution is given with the associated first integral of energy. A subset of the solution is shown to be non-ergodic whereas the full solution is shown to be ergodic. The first integral of energy is applied to the study of these fields to prove that the equilibrium points of such magnetic configurations are saddle points. Finally, the potential function of the first integral of energy is shown to be a member of the Helmholtz family of solutions. Numerical results corroborate the theoretical conclusions and demonstrate the robustness of the energy integral, which remains constant for arbitrarily long computing time

The idea of the university and problems concerning education, indoctrination and the role of philosophy in the university

Theoretical reflection about the university and education in general cannot be abstracted or isolated from the complex modern society in which it has to function. Therefore, philosophical reflection about the problems stated in the title of this article must keep in mind the structure of the university and education and must also give account of the perversion of education called “indoctrination”. This has to be done within the context of the interrelationships of these phenomena in society. In order to obtain a clear picture of these phenomena it is necessary to see them in context and to isolate them from the societal configuration of the complex society of the twentieth century. In this academic undertaking it might prove that either the one or the other aspect of the problem has at some stage been over-accentuated; but this is an academic risk one must be willing to run when trying to grasp the complexity of reality with its immense structural variety

Differential rotation and angular momentum

Differential rotation not only occurs in astrophysical plasmas like accretion disks, it is also measured in laboratory plasmas as manifested in the toroidal rotation of tokamak plasmas. A re-examination of the Lagrangian of the system shows that the inclusion of the angular momentum’s radial variation in the derivation of the equations of motion produces a force term that couples the angular velocity gradient with the angular momentum. This force term is a property of the angular velocity field, so that the results are valid wherever differential rotation is present