A video-oculographic study of acute vestibular syndromes.

OBJECTIVES: To quantitate the vestibulo-ocular reflex (VOR) gain in patients with acute vestibular neuritis (VN) and repeat this daily using a portable video head impulse test device to assess vestibular recovery in the acute stage of VN. MATERIALS AND METHODS: We enrolled adults with symptoms and signs of VN presenting to the emergency department within 48 h of symptom onset. We recorded the eye movement response to rapid head impulses using the ICS Impulse(™) video head impulse test device on each day of their hospital admission. RESULTS: There were eight patients (75% men, aged 35-85 years) who had marked variation in their initial vestibulo-ocular reflex gains. Three patients had vestibulo-ocular reflex gains in the normal range initially, despite having physical signs of VN. Two patients had initial contralesional gains below the normal range, associated with markedly reduced ipsilesional gains. Most patients' vestibulo-ocular reflex gains increased during admission, but four patients' ipsilesional gains remained in the abnormal range. Patients with lower vestibulo-ocular reflex gains were less likely to improve into the normal range. No patient with initially abnormal VOR gain recovered normal vestibulo-ocular reflex gain along with resolution of physical signs. CONCLUSION: Early video head impulse testing in the emergency department and each day of admission is feasible and well tolerated. There is marked variation in VOR gain in patients with symptoms and signs of VN, and low initial VOR gains are a predictor for low VOR gains on subsequent days. Improvement in VOR gains was seen in most patients.

Strain-Biased PLZT Input Devices (Page Composers) for Holographic Memories and Optical Data Processing.

PLZT-7/65/35 is a ferroelectric ceramic with strong electrooptic properties and memory; it is switched through transparent electrodes when mechanically strained. Matrix addressed x-y page composers for interfacing electrical and coherent optical systems are being fabricated with PLZT. Switching voltages are 50-300 V. Optical efficiencies greater than 40% have been achieved. Strains near 2.4 x 10(-3) mm/mm permit half-wave retardation switching in 100-micro-thick plates with 80-V read-in and 190-V erase levels (60 Hz hysteresis data). A 128 x 128 element array can operate at 10(7) bits/sec with 10-microsec switching in a row at a time mode. Half-select disturbances affect contrasts. Applications in displays are also feasible.

High speed holographic digital recorder.

Concepts, feasibility experiments, and key component developments are described for a holographic digital record/reproduce system with the potential for 1.0 Gbit/sec rates and higher. Record rates of 500 Mbits/sec have been demonstrated with a ten-channel acoustooptic modulator array and a mode-locked, cavity-dumped argon-ion laser. Acoustooptic device technology has been advanced notably during the development of mode lockers, cavity dumpers, beam deflectors, and multichannel modulator arrays. The development of high speed multichannel photodetector arrays for the readout subsystem requires special attention. The feasibility of 1.0 Gbits/sec record rates has been demonstrated.