Suchergebnisse

This article will make an attempt to explain the reasons why local and very often social rather than political issues, played such an important role in black South African politics in the period 1920-1950.

It is shown that the usual MHD approximation is not suitable for the description of the Kelvin-Helmholtz instability of the terrestrial magnetopause. Indeed such a description implies an ideal magnetopause with a smooth continuous variation of the plasma and field parameters occuring in an extended current sheet. However, the actual magnetopause and its adjacent plasma boundary layer are highly irregular, both spatially and temporally. Therefore, finite ion Larmor radius effects do not represent small corrections. It is argued that these small-scale inhomogeneities can change drastically the usual large-scale description of the magnetopause oscillations.

Les interactions gyrorésonnantes entre particules chargées et ondes hydromagnétiques jouent un rôle important dans de nombreux problèmes rencontrés dans l'étude de la magnétosphère et du vent solaire.
Dans cet article, on formule analytiquement un invariant généralisé pour le mouvement d'une particule chargée dans le champ électromagnétique d'une onde hydromagnétique polarisée linéairement. Cette onde plane se propage dans la direction d'un champ magnétique uniforme et on suppose que l'amplitude de la composante magnétique de l'onde est faible. A l'aide d'une transformation canonique simplificatrice, l'invariant J est développé jusqu'au premier ordre en l'amplitude de la modulation. Dans l'espace des phases, on montre que les courbes J = constante reproduisent de manière satisfaisante les trajectoires de phase calculées numériquement à partir des équations de mouvement.

This paper links campaign resources and voter calculus through a microeconomic optimization framework. I assume that candidate policy positions are fixed while personal valence scores and the salience of issue dimensions are malleable. Low valence candidates with many proximate competitors in the policy space will focus on building valence. High valence candidates who are relatively "unclustered" in the policy space will focus on manipulating issue salience. Resources devoted to diminishing others' valence scores will increase as the number of viable candidates decreases. The model's results are tested, where feasible, using data from the Democratic Party primary of 2004. Adapted from the source document.