ABSTRACT
We have developed a robust, nonlinear differentiating digital filter for the estimation of eye velocity from an eye-position signal. This filter is equally applicable to a large variety of other biomedical signals. The filter is implemented by taking an odd number of two-point differences around the point of interest and then selecting the median difference. Dividing the median difference by the time interval yields the derivative of the input signal. The Robust Differentiator (RD) is a classic order-statistic filter consisting of a bank of linear filters (the two-point differences) followed by the median operation to select one difference for the derivative calculation. The RD has no impulse response function and eliminates the "ringing" that is typical of all linear filters. The RD not only performs better than the FIR differentiating filters for impulse noise but is equally effective for both broad-band and narrow-band Gaussian noise. The RD "bandwidth" is adjustable by selecting the interval for the two-point differences.
Subject(s)
Eye Movements , Signal Processing, Computer-Assisted , HumansABSTRACT
Pursuit tracking eye movements were recorded and analyzed from a group of US Air Force Pilot Candidates (PCs). The PCs ranged in age from 21 to 27 with a median age of 23. All were college graduates and recently passed a Flying Class I physical exam. These PCs comprise a highly motivated, intelligent group of young subjects. Pursuit tracking was assessed by having the subjects track a small spot of green light moving sinusoidally in the horizontal plane at frequencies from 0.2 to 1.0 Hz in 0.2 Hz increments. Peak-to-peak target amplitude was 40 degrees. Eye movements were recorded using an infrared reflectance device. Eye movements were separated into smooth pursuit (SP) and saccadic (SA) components. Tracking performance was evaluated by computing the gain and asymmetry of the SP component and the percentage of tracking movements contributed by the SA component. Both mean values and variance of the tracking performance of the PCs were not found to be statistically different from a group consisting of both flying and nonflying Air Force personnel.
Subject(s)
Pursuit, Smooth/physiology , Saccades/physiology , Adult , Analysis of Variance , Aviation , Female , Humans , Male , Military Personnel , Reference ValuesABSTRACT
A case report of cat-scratch disease manifest as submandibular lymphadenopathy has been presented. The etiology, histopathology, symptoms, diagnosis, treatment, and complications of cat-scratch disease have been discussed. Cat-scratch disease should be considered in the differential diagnosis of all equivocal cases of unilateral lymphadenopathy of the head and neck.
Subject(s)
Cat-Scratch Disease/diagnosis , Salivary Gland Diseases/diagnosis , Submandibular Gland Diseases/diagnosis , Adult , Animals , Cats , Humans , MaleABSTRACT
Fibromatosis colli is a distinctive form of fibromatosis that develops in the sternocleidomastoid muscle of the newborn. When the diagnosis is certain, the treatment of choice is frequent passive stretching of the sternocleidomastoid muscle. Open tenotomy or excision of the mass may be needed if the problem persists beyond the age of 6 months. A case report is presented, and the literature is reviewed.
