With an adequate supply of matter, the inward drifting of dust particles induced by the Poynting-Robertson effect can lead to the formation of a shell or disk-like structure around the source of radiation. In a steady state, the Poynting-Robertson effect produces a spatial density of dust in the form of 1/r which in turn gives rise to a mid

Contents: 1. Introduction. 2. The virial equation. 3. Components of kinetic energy. 4. Gravitational potential energy. 5. Validity of putting r.h.s. terms zero. 6. A new relationship. 7. The early universe. 8. Estimates of Ω0 and neutrino mass. 9. Discussion and conclusion. Appendix: The virial equation for massive and massless particles in any set

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First order Fermi acceleration is an efficient mechanism to produce relativistic particles in strong astrophysical shocks. The authors have developed a model using this theory to explain the non-thermal emission from non-relativistic jets in quasars and AGNs.

The use of a liquid crystal as an optical modulator for use with a resonant scattering spectrometer has been investigated. Preliminary data indicate that using this simple device velocity signals corresponding to 5 minute oscillations have been detected.

The column density distribution of the local interstellar medium (LISM) towards a sample of 15 fast rotators observed with IUE at high resolution is reported. The targets are closer than 200 pc, and most of them have lines of sight not previously investigated. Hydrogen column densities are inferred using zinc, known to be little depleted. The