Biomedical subjects
Publications and source records attributed to F K Hsu.
A 5-year-old boy presented with refractory microcytic anemia, growth failure, and markedly elevated sedimentation rate. Computed tomographic (CT) and upper gastrointestinal study disclosed an ulcerated 9-cm large gastric mass, which proved to be an inflammatory myofibrohistiocytic proliferation (IMP). The characteristic clinical and radiologic features of this rare entity are herein reviewed.
Glissades are the slow, gliding eye movements often appended to the end of human saccadic eye movements. They have been used as an aid in diagnosing disease states, eg, multiple sclerosis and vascular lesions. Glissades are a consequence of a mismatch between the sizes of the pulse and step components of the pulse-step motoneuronal controller signals. This physiological and simulation study shows that glissadic overshoot is caused by pulse width errors and not by pulse height errors. This implies that the CNS can control the firing frequencies and recruitment of motoneurons more precisely than it can control the duration of the high-frequency motoneuronal saccadic burst.
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A non-linear sixth order homeomorphic model, fitted with parameters based on eye movements and physiological data, was tuned so that it provided good simulations for the shapes of the magnitude, velocity and acceleration trajectories. Excellent quantitative agreement was obtained in terms of the Main Sequence diagrams for human eye movements. Parametric sensitivity analysis was done for a saccade of ten degree amplitude, a physiologically normal magnitude at which experimental data is both abundant and relatively noise free. Among the many useful results of this sensitivity analysis are that pulse width (PW) and pulse height (PH) were confirmed as the two controlling parameters for the human eye movement model. Output behavior was relatively insensitive to variations of the passive elements of the plant. This analysis also pointed out that more physiological data are needed to understand the role of the non-linear force-velocity relationship of the extraocular muscles.