Magnetohydrodynamic Model of Equatorial Plasma Torus in Planetary Nebulae

Some basic structures in planetary nebulae are modeled as self-organized magnetohydrodynamic (MHD) plasma configurations with radial flow. These configurations are described by time self-similar dynamics, where space and time dependences of each physical variable are in separable form. Axisymmetric toroidal MHD plasma configuration is solved under the gravitational field of a central star of mass $M$. With an azimuthal magnetic field, this self-similar MHD model provides an equatorial structure in the form of an axisymmetric torus with nested and closed toroidal magnetic field lines. In the absence of an azimuthal magnetic field, this formulation models the basic features of bipolar planetary nebulae. The evolution function, which accounts for the time evolution of the system, has a bounded and an unbounded evolution track governed respectively by a negative and positive energy density constant $H$.Comment: 14 figure

Global axisymmetric stability analysis for a composite system of two gravitationally coupled scale-free discs

In a composite system of gravitationally coupled stellar and gaseous discs, we perform linear stability analysis for axisymmetric coplanar perturbations using the two-fluid formalism. The background stellar and gaseous discs are taken to be scale-free with all physical variables varying as powers of cylindrical radius $r$ with compatible exponents. The unstable modes set in as neutral modes or stationary perturbation configurations with angular frequency $\omega=0$.Comment: 7 pages using AAS styl

Values Driving Internationalization of Higher Education and Its Influence on International Student Mobility in Two Distinct Contexts Zhejiang Normal University in China and Jimma University in Ethiopia

The main purpose of this comparative study was to understand values driving internationalization of higher education and how these values influence international student mobility in China and Ethiopia. The meaning, rationale and strategies of internationalization was thoroughly explored with the aim of portraying contextual meaning and drawing lesson from experiences. Qualitative case based two level design national and institutional, is employed that allowed thick data collection by exploring the dynamic relationship within and across cases.  Semi structured face to face interview with purposely selected participants were conducted. Participants were ministry of education higher education officers from Ethiopia, professors and university leaders, relevant office experts from both cases, all together 61 participants taken part in the study. Policy documents and institutions strategic plan and relevant literature were thoroughly consulted. The data is collected, analyzed, thematically interpreted case by case, not to distort the contextual color/meaning/ and displayed in cross-case comparative matrices to support understanding of the phenomenon in both contexts. The cases display similarity in two conceptual issues-meaning and rationale and display difference in practical matters-strategies. Internationalization in both cases perceived as a means to respond to local and global needs by producing competent global graduates. The major value deriving internationalization at both cases found imbedded in their national development priorities. Hence the meaning of internationalization indicated the felt need of the country, while these needs implied the strategy adopted that directly influenced international student mobility in both cases. Keywords: value, internationalization, international student mobilit