This paper examines the recent introduction of the AIS to the ship's bridge and its potential impact on the safety of marine navigation. Research has shown that 80 to 85% of all recorded maritime accidents are directly due to human error or associated with human error. Safety is an important element of marine navigation and many people at different levels are involved in its management. The safe and efficient performance of joint systems, is heavily dependent upon how functions are allocated between the human and the machine. This paper investigates different regulations, supervision for proper use, training, and management of AIS users. It uses previous research and three separate AIS studies to identify problems. The potential of the AIS to cause problems is analysed. The classic human factor '' Swiss Cheese '' Model of system failure has been modified for the AIS to investigate a possible accident trajectory. The paper then concludes with recommendations and suggestions for improvements and further work. K E Y W O R D S 1. Human error. 2. AIS. 3. Marine navigation safety. 4. Training.

Normal subjects learned to identify words through a tactile vocoder. The vocoder employed 16 filter channels, each with a bandwidth of 1/3 octave, with center frequencies ranging from 200-8000 Hz. The output of each filter was detected and after logarithmic amplification the resulting outputs were transmitted to a 16-channel solenoid array placed on the subject's ventromedial forearm. Words, spoken "live voice," were used as stimuli; the subject was able to feel both the vocalization of the reader and herself and, most importantly, extensive training was provided. In 40.5 h one subject learned 70 words and a second subject reached criterion on 150 words in the comparatively short time of 55 h. Words that were poorly identified initially were identified more readily with increased experience. Phonetic identification tests showed that the features of voicing, nasality, and frication were reliably recognized, indicating the tactile vocoder will be useful in providing information to complement lipreading. Finally, subjects learned rapidly to generalize word-learning to unfamiliar readers.

In a previous experiment [P. L. Scilley, "Evaluation of a vibrotactile auditory prosthetic device for the profoundly deaf," unpublished Masters thesis, Queen's University, Kingston, Canada (1980)] two normal subjects learned to identify 70 and 150 words, respectively, using the Queen's Tactile Vocoder. In the present experiment, the most advanced subject continued word learning until a tactile vocabulary of 250 words was acquired. At this point randomized tests were given to obtain an indication of final performance level. From these data conditional probabilities of correct response for each stimulus word and significant confusions were obtained, which provides insight into the advantages and present limitations of the tactile vocoder.

applicable.4 The international stroke trial plans to recruit about 20 000 patients from 500-600 hospitals in 40 countries worldwide and should be reporting its results in 1996. The pharmaceutical industry is investing large amounts of money in developing and testing several new compounds, which are now entering clinical trials in patients with acute stroke. These compounds have a common aim: to protect neurones from the damaging effects of ischaemia by inhibiting excitatory amino acid neurotransmitters such as glutamate, by reducing the influx of calcium, and by reducing concentrations of free radicals. Other neuroprotective agents such as magnesium also seem promising. In future, if they are proved to be safe and effective, some of the simpler treatments may be offered routinely to most patients with acute stroke. Treatments with a higher risk of complications may be offered only to a selected few. Whatever the results of the current trials of medical treatnent, one thing is certain: hospitals must act now to develop organised systems ofcare for patients with acute stroke.

The experiments described are part of an ongoing evaluation of the Queen's University Tactile Vocoder, a device that allows the acoustic waveform to be felt as a vibrational pattern on the skin. Two prelingually profoundly deaf teenagers reached criterion on a 50-word vocabulary (live voice, single speaker) using information obtained solely from the tactile vocoder with 28.5 and 24.0 hours of training. Immediately following word-learning experiments, subjects were asked to place 16 CVs into five phonemic categories (voiced & unvoiced stops, voiced & unvoiced fricatives, approximants). Average accuracy was 84.5%. Similar performance (89.6%) was obtained for placement of 12 VCs into four phonemic categories. Subjects were able to acquire some general rules about voicing and manner of articulation cues.