Supernova Interaction with a Circumstellar Medium

The explosion of a core collapse supernova drives a powerful shock front into the wind from the progenitor star. A layer of shocked circumstellar gas and ejecta develops that is subject to hydrodynamic instabilities. The hot gas can be observed directly by its X-ray emission, some of which is absorbed and re-radiated at lower frequencies by the ejecta and the circumstellar gas. Synchrotron radiation from relativistic electrons accelerated at the shock fronts provides information on the mass loss density if free-free absorption dominates at early times or the size of the emitting region if synchrotron self-absorption dominates. Analysis of the interaction leads to information on the density and structure of the ejecta and the circumstellar medium, and the abundances in these media. The emphasis here is on the physical processes related to the interaction.Comment: 22 pages, 7 figures, to appear as a Chapter in "Supernovae and Gamma-Ray Bursts," edited by K. W. Weiler (Springer-Verlag

Individual and contextual influences on the affective commitment of retail salespeople

Salesperson characteristics as well as managerial approaches have been found to play an important role in the development of positive attitudes by salespersons towards an organisation. This study integrates these two research areas to investigate the personal and contextual antecedents of affective organisational commitment of retail salespeople. Fit theory and the literature on person-situation interaction provide the theoretical basis for explaining how salesperson selling skills, job liking and empowerment individually and jointly influence affective commitment. A multilevel modelling approach is used to analyse data from 105 sales managers and 419 salespeople. Findings reveal that salespersons&rsquo; affective commitment is influenced by their selling skills, degree of job liking, tenure and empowerment. The results also indicate that the impact of selling skills on affective commitment is higher when empowerment is high. Based on the study&rsquo;s findings, implications for managing salespeople as well as limitations and suggestions for future research are offered.</p