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Biomedical subjects

John D Enderle

Publications and source records attributed to John D Enderle.

7 recordsLinked to original sources
PubMed2003

Dynamic modeling of the neck muscles during horizontal head movement. Part II: Model construction in Pro/Engineer.

This paper describes the next phase of research on a parametric model of the head-neck system for dynamic simulation of horizontal head rotation. A skull has been imported into Pro/Engineer software and has been assigned mass properties such as density, surface area and moments of inertia. The origin of a universal coordinate system has been located at the center of gravity of the T1 vertebrae. Identification of this origin allows insertion and attachment points of the sternocleidomastoid (SCOM) and splenius capitis to be located. An assembly has been created, marking the location of both muscle sets. This paper will also explore the obstacles encountered when working with an imported feature in Pro/E and attempts to resolve some of these issues. The goal of this work involves the creation of a 3D homeomorphic saccadic eye and head movement system.

Computer Simulation↗
PubMed2003

Knowledge management system for benchmarking performance indicators using statistical process control (SPC) and Virtual Instrumentation (VI).

Healthcare is ever changing environment and with the Joint Commission for the Accreditation of Hospital Organization (JCAHO) emphasis on quality improvement during the past several years, and the cost-focused healthcare reforms of the 1990s, benchmarking with peer comparison, and more recently benchmarking against competitors, has taken on a new emphasis. All acute healthcare organizations accredited by JCAHO now require participation in a program titled ORYX, which is designed to use comparisons with other organizations and promote national benchmarks. The knowledge management system designed assists clinical engineering department to convert vast amounts of available data into information, which is ultimately transformed into knowledge to enable better decision-making. The systems assist in using the data as a comparison tool, to compare the performance internally and also compare performance with peer organizations using the same measures within the same measurement system. Collectively, these applications support better, faster data-driven decisions. This tool provides fast and easy access to financial and quality metrics to clinical engineering department managers, which increases their ability to perform sophisticated analysis to develop accurate models and forecasts, and make timely, data driven decisions. The project also provides a platform by means of which clinical engineering departmental procedures, data, and methods can be assessed and shared among institutions.

Artificial Intelligence↗
PubMed2003

The Eye Tracker System--a system to measure and record saccadic eye movements.

The Eye Tracker System, built at the University of Connecticut at Storrs in the Biomedical Instrumentation Lab, consists of three separate and distinct units brought together as a whole system to measure saccades. A seven row, eleven columned array of LEDs mounted on five degree centers along a concave surface provides targeting for the Eye Tracker System wherein the subject eye follows a pattern of illuminated LEDs as determined by the experimenter. The target system is digitally driven by serial inputs from the Main Command System. Subject positioning is aided by the concave surface of the Target System. The System Console employs a multiple regression Operating System to predict Eye Position. Twenty-four channels utilizing the theory of Infrared Light Reflective Differentiation make measurements of the location of the eye. These optoelectronics are mounted in a specialized head-mounted transducer. The optoelectronics are mounted on the interior of a parabolic surface automatically aiming them towards the limbus. The transducer is styled after an ophthalmologist's test frames and is comfortably worn and adjustable in size to fit any subject. The Main Command System authored under G programming language (LabView) provides a graphic user interface (GUI) that controls the generation of the target pattern. The Main Command System also coordinates the programs that acquire all data, the regression algorithm for the real-time prediction of the eye position and the initial calibration of the system. In addition the application is able to save a retrieve data for further analysis.

Diagnosis, Computer-Assisted↗
PubMed2002

Neural control of saccades.

Quantitative models of the oculomotor plant and control of the saccadic eye movement system are presented in this chapter. Oculomotor plant models described here are linear, including a second-order model by Westheimer (1954), Bahill et al. (1980) and Enderle et al. (2000). The model of the saccade generator is initiated by the superior colliculus and terminated by the cerebellar fastigial nucleus that operates under a time optimal control strategy. A common mechanism for all types of saccades is described, including those with dynamic overshoot and glissadic behavior. Conflicting evidence exists regarding the operation of the excitatory burst neuron during saccades. The excitatory burst neuron operates within two states: complete inhibition, and without inhibition that is characterized by high firing at rates of up to 1000 Hz. While there is direct evidence of projections from the superior colliculus to the paramedian pontine reticular formation, there is conflictory evidence regarding the connections from the superior colliculus to the excitatory burst neuron, with the most recent experimental results supporting no direct connections. A model of the excitatory burst neuron is described using a Hodgkin-Huxley model of the neuron that fires at 1000 Hz automatically and without stimulation when released from inhibition. SIMULINK simulations using this neuron model have all of the characteristics of the excitatory burst neuron firing rate during a saccade. This model eliminates the need to introduce BIAS inputs that causes bursting in some models of the saccade generator. Such a model is also appropriate for modeling the Omnipause neurons.

Algorithms↗
PubMed2002

The operating version of the Eye Tracker, a system to measure saccadic eye movements.

The operating version of the Eye Tracker, a transducer and system using a technique to bounce infrared light off the eye to measure saccadic eye movements in any X-Y position is presented in this paper. Discussed is the method of reading and analyzing eye movement data using a 24-channel infrared optoelectronic array and computer algorithms that utilize a linear regression model to interpret and determine eye location, the 24-channels used to ensure accurate reading of eye position. Accuracy is also maintained by a signal processing system that attenuates incident light as well as ambient light. Also discussed is a novel method of mounting the infrared array on hemispherical shaped eyepieces that in turn are mounted on goggles styled after an ophthalmologist's test frames that is comfortably worn and adjustable in size to fit any subject. A computer controlled, wall mounted light bank facilitates targeting for eye movements. The Eye Tracker is built to meet standards of a professional medical device manufacturer following typical mechanical, electrical, and safety techniques unique to device packaging.

Diagnosis, Computer-Assisted↗
PubMed2002

Dynamic modeling of the neck muscles during horizontal head movement.

This paper presents modeling and simulation of superficial neck muscle movement in the horizontal plane (yaw). The parametric muscle model was constructed using Pro/Engineer 2000i Student Edition, Parametric Technologies Corp, and simulated using Pro/Mechanica. Pennation angles, force-tension, force-generation and rate of muscle activation data were obtained from anatomic and physiological studies. Saccadic eye movement models developed by G. Alexander Korentis and John Enderle also provided the basis for this model.

Biomechanical Phenomena↗