[1] Appearance of anomalies in the atmosphere before earthquakes (EQs) has been verified, through observation of anomalous transmission of VHF electromagnetic (EM) waves beyond line-of-sight. Anomalous increase of the received intensity for a few minutes -several hours on a day was identified by the previous 15-day running median and its inter-quartile range. The cross-correlation between the EQ occurrences and the anomalies shows that the appearance of anomalies was significantly enhanced within 5 days before M ! 4.8 EQs. The one-day average number of the anomaly appearance within 5 days was found 2.4 times larger than that of other days. Through the polarization measurement of the received EM waves, the anomalies were found to occur in the atmosphere.

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Monochromatic x-ray emission is predicted for MeV channeled electrons/positrons. The mechanism of this radiation is intuitively understood as diffraction of virtual channeling radiation into the direction of the Bragg angles with respect to the electron beam. Our numerical calculations predict that spectral density of the emitted x rays is about ten times larger than that of parametric x-ray radiation.

A bound-state problem is solved for an extended Bethe-Goldstone equation which includes the shortrange positron-electron interaction. It is concluded by numerical calculation that positronium formation is not possible in the usual range of the density parameter r,.