Germanium ions have been implanted in fused silica using ion beams having energies of 3 and 5 MeV and doses ranging from 1×1012 to 5×1014 ions/cm2. For wavelengths shorter than 400 nm, the optical absorption increases strongly with two absorption bands appearing at 244 and 212 nm. The ion-induced optical absorption can be bleached almost completely by irradiation with 249 nm excimer laser light. Ion implantation also increases the refractive index of silica near the substrate surface. At 632.8 nm a refractive index increase of more than 10-2 has been measured. This decreases by 4×10-3 upon bleaching with 249 nm light.
We discuss two-party mutual authentication protocols providing authenticated key exchange, focusing on those using asymmetric techniques. A simple, efficient protocol referred to as the station-to-station (STS) protocol is introduced, examined in detail, and considered in relation to existing protocols. The definition of a secure protocol is considered, and desirable characteristics of secure protocols are discussed.
The ethnographic treatment of "rites de Passage" is discussed with reference to
material relating to religious initiation. It is suggested that the major transitions
engendered through the Tibetan Buddhist Tantric W a n g Kur rituals may be profitably
analyzed not simply as changes in social status but rather as tools for the re-ordering
of phenomenology which are designed to engender long-term alterations in the
initiates' experience of the world. The initiation provides a rationale and instruction
conjunctive with ritual technique which is consciously designed to globally and
permanently alter the consciousness of the practitioner. Suggestions for studies of
rites of passage which take into account this dimension of the ritual control of
experience are offered.