A comparison of two computer access systems for functional text entry.

OBJECTIVE: Functional written communication, an important goal in the rehabilitation of persons with tetraplegia, frequently is met through the use of personal computers and alternative computer access systems. To make informed decisions about alternative access systems, the therapist needs information on the efficacy of the available choices. The purpose of this study was to investigate the effectiveness of two commercially available systems for text entry, the traditional mouthstick and the Prentke Romich HeadMaster. METHOD: Participants were a 25-year-old man and 76-year-old woman who both functioned at a C5 neurological level. Neither participant had previous experience with either system for text entry. A single-subject research design was used whereby Participant 1 experienced six phases of treatment (i.e., CBCBCB, where C = mouthstick and B = HeadMaster), and Participant 2 experienced four phases of treatment (i.e., BCBC). RESULTS: Participant 1 achieved a maximum rate of text entry of 5.85 wpm with both the HeadMaster and the mouthstick, whereas Participant 2 achieved a maximum rate of 7.15 wpm with the mouthstick and 4.85 wpm with the HeadMaster. Results from this study were similar to the results from previous comparison studies of persons with severe disabilities who had no experience with alternative computer access systems. CONCLUSION: Both participants were able to use both systems successfully; however, their respective rates of text entry were too slow to be functional in most employment situations.

Sintered superhard materials.

Diamond or cubic boron nitride particles can be sintered into strong masses at high temperatures and very high pressures at which these crystalline forms are stable. Most of the desirable physical properties of the sintered masses, such as hardness and thermal conductivity, approach those of large single crystals; their resistance to wear and catastrophic splitting is superior. The sintered masses are produced on a commercial scale and are increasingly used as cutting tools on hard or abrasive materials, as wire-drawing dies, in rock drills, and in special high-pressure apparatus.

Absolute pressure measurements and analysis of diamonds subjected to maximum static pressures of 1.3-1.7 Mbar.

Force per unit area measurements made in the megabar pressure cell, independently of other pressure calibration systems, are consistent with the ruby R1 scale of Mao, Bell, Shaner, and Steinberg and its extrapolation to 1.4 Mbar. Physical analysis of diamond anvils removed after experiments to maximum pressures of 1.3-1.7 Mbar suggests that the nitrogen platelet concentration may be related to the strength of the diamonds. The pressure face of one of the diamonds from the 1.7-Mbar experiment was deformed plastically by a macroscopic amount.