Quasilinear Drift Of Cosmic Rays In Weak Turbulent Electromagnetic Fields

A general quasilinear transport parameter for particle drift in arbitrary turbulence geometry is presented. The new drift coefficient is solely characterized by a nonresonant term and is evaluated for slab and two-dimensional turbulence geometry. The calculations presented here demonstrate that fluctuating electric fields are a key quantity for understanding quasilinear particle drift in slab geometry. It is shown that particle drift does not exist in unpolarized and purely magnetic slab fluctuations. This is in stark contrast to previous models, which are restricted to slab geometry and the field line random walk limit. The evaluation of the general transport parameter for two-dimensional turbulence geometry, presented here for the first time for dynamical magnetic turbulence, results in a drift coefficient valid for a magnetic power spectrum and turbulence decay rate varying arbitrarily in wavenumber. For a two-component, slab/two-dimensional turbulence model, numerical calculations are presented. The new quasilinear drift, induced by the magnetic perturbations, is compared with a standard drift expression related to the curvature and gradient of an unperturbed heliospheric background magnetic field. The considerations presented here offer a solid ground and natural explanation for the hitherto puzzling observation that drift models often describe observations much better when drift effects are reduced.Comment: 23 pages, 6 figures, accepted for publication in Ap

Geografiese invloede op ons beskawingspatroon

Die opskrif van hierdie lesing lui: „Geografiese invloede op die Suid-Afrikaanse Beskawingspatroon”. Onmiddellik laat dit die vraag ontstaan wat ’n geografiese invloed nou eintlik is: hoe word dit onderskei van bv. ’n geologiese of sê m aar ’n plantkundige invloed, en is daar nou werklik iets soos ’n geografiese invloed? Met ’n lang bespreking van hierdie vrae wil ek u nie oorval nie: laat my volstaan met die verklaring dat ek vir die doeleindes van hierdie beskouing uitgegaan het van die standpunt dat die geografie die verhouding bestudeer tussen die mens en sy omgewing en dat ek as geografiese in­ vloede geneem het alle invloede wat kan uitgaan van die fisiese omgewing in die breedste sin van die woord

School discipline and the delictual negligence test for teachers – a case in point

From text: Proper discipline is a prerequisite for safety in schools. In addition to creating an environment conducive to learning, school discipline is essential to ensure the safety of staff and learners. School discipline includes the implementation of reasonable measures to secure the safety of staff and learners as well as responsible behaviour by learners. The failure of school staff and authorities to enforce discipline may have serious educational and legal consequences. Where such failure amounts to conduct that causes personal injury and financial loss, liability for the recovery of such loss may follow if all the requirements for a delict are met