© Springer Science+Business Media New York 2014. This model was simulated on a digital computer and comparisons to the paradigm experimental responses were performed, demonstrating a fit to each of the observed conditions. The results of this work can be used to develop robust iris recognition algorithms that handle the effects of pupil dilation. The consistent finding was the amplitude dependence of the speed of the fastest voluntary efforts: the larger the amplitude, the faster the contraction. A quadratic system may be built from simple linear terms of known dynamics and a multiplier.
Detection, representation, and identification of nonlinearities in biological systems are considered. Sampled data models of the human operator in a control system. The mean diameter of the human pupil was measured during stimulation of the eye with light of sinusoidally varying intensity and during stationary illumination with the corresponding average intensity. The increase of the rate of rise of isometric tension or of the velocity of isotonic movements with rising amplitude was linear. Bei Frequenzen der Belichtung über 2 Hz verhält sich die Pupille nahezu starr. Second-order models are shown to be task-specific special cases of the input-output behavior of the eighth-order model, while the more complex biophysical models are hypothesized to have insignificant advantages and many disadvantages over the Hill-based model during normal human movement.
Stark is survived by his partner of 18 years, Jill Strohn of Berkeley, Calif. This page is about the neurologist. However, this fecundity also presents special problems; the wealth of published data often appears confusing and contradictory, and has occasionally led to heated controversy. When pupillary suppression is maximal, the average change in pupil area caused by a flash is found to be only about 10% of the average area change produced by control flashes of identical intensity presented during steady fixation. This technique will permit objective diagnostics of pathologies presented in people submitted in biomechanic studies and pre-post surgery analysis.
Therefore, an analysis of the input-output relations between parameters of the motion and motor outputs to agonist and antagonist, both under normal conditions and following cerebellar lesions, becomes a logical necessity. These results did not change when the inertial mass was doubled by loading the arm with an additional mass. What is then the function of the externalised painting? Furthermore, current research work on iris deformation does not take into account the mechanical properties of the iris tissue nor the cause of deformation from the iris muscle activity. The main modulation pattern was retained during single-limb treadmill walking. Small pupils, operating under photopic conditions, show tonic responses to step increases of light and high gains; thus the pupil is a good regulator of light. Although more complex behavior can be observed for parameter values which gave complicated dynamics in the model, there is not a one-to-one correspondence between the observed and predicted results.
Knee and ankle motions were out of phase in the first part of the cycle; knee extension occurred simultaneously with ankle flexion. New, non-invasive methods have opened the way to direct observation of the human brain in action. These modes primarily influence the shape of the oscillation. These simulations found that cerebellar patients' neurological control signals were altered with respect to those of normal subjects, and suggest that the electromyographic activity of cerebellar patients may comprise at least five bursts of activity whereas normal subjects typically exhibit only three. The disturbances of limb position perception and limb velocity perception depended on the vibration rate in distinctly different ways. Comparison of simulation results showed direct correspondence between positive off-diagonal 2nd-degree kernel values and the pupillary-escape-like effect demonstrated by the heuristic model. The goal was to establish changes in the control loop corresponding to behavioral changes observed on different support surfaces.
An application to a physiological control system demonstrates the practically of this algorithm as well as suggesting the prospective usage of the kernel method for nonlinear-system analysis in the future. Three structurally different types of models have evolved over the years to describe muscle-joint systems. A hand control model is proposed. The NewTek Video Toaster is the base of the video processing system used combined with ophthalmologic instrumentation. The critical duration was measured at threshold for the pupillary light reflex and visual perception, using seven subjects and three background levels. We conclude that humans can use feed-forward changes in multi-finger synergies anticipatory synergy adjustments in anticipation of a predictable perturbation.
This same model structure has been used successfully for eight different muscle-joint systems, ranging in size from knee flexion-extension to eye rotation--the only difference between the models is in the parameter values. This extensively revised and updated fourth edition reflects new developments at the burgeoning interface between physics and biomedicine. Rosenblith and I have been doing concerning the nature of the electroencephalogram, and in particular of the alpha rhythm, it has occurred to me to use the model of a system of random nonlinear oscillators excited by a random input. His father Edward Stark was a chemical engineer trained at , and Lawrence credited his early interest in engineering to him. A model of the pathways controlling the size of the human pupil is presented. Intended for advanced undergraduate and beginning graduate students in biophysics, physiology, medical physics, cell biology, and biomedical engineering, this wide-ranging text bridges the gap between introductory physics and its application to the life and biomedical sciences. Computer simulation results on quadratic systems with building elements of various time constants indicate reasonably that the larger time constant term before multiplication dominates in the envelope of the off-diagonal kernel curves as these move perpendicular to and away from the main diagonal.
A nonlinear eighth-order agonist-antagonist muscle model is identified, based on engineering analysis and design criteria, as the desired structure for the broad-range study of a variety of fundamental human joint movements. It is analysed using an extended parameter sensitivity analysis, that is used in both direct sense, as a model fitting tool, and in the indirect sense as a guide to experimental design. The last few of these were devoted to the application of my ideas to problems in the statistical mechanics of gases. Whatever they are, linear or not, is beside the point, for in either case the same difficulty of analysis arises. We applied vibration at various rates to the biceps tendon of a passive, restrained arm in normal human subjects and measured its effect on the perception of forearm position and the perception of forearm velocity. He worked at and and as a doctor in the during the. This work is both new and tentative, and I found that I had to supplement my course by the writing over of these with the help of Professer Y.
Through decomposition of the control loop, we found that behavioral change is not necessarily due to a change in control strategy, but in the case of different support surfaces, is linked to changes in properties of the plant. Maintaining upright bipedal posture requires a control system that continually adapts to changing environmental conditions, such as different support surfaces. We discuss a possibility that anticipatory postural adjustments may represent a particular case of the phenomenon of anticipatory synergy adjustments and suggest a hierarchical control scheme that incorporates a possibility of independent control over the output of a multi-element system and covariation patterns among outputs of its elements. The first, based on an input-output analysis of a given task, results in a simple second-order differential equation description that is adequate over a certain movement operating range. A quantitative transfer function for predictable inputs serves further to define the hand's input adaptive characteristics.