Abstract: Systems and methods derive relative eye position by tracking a boundary such as the limbus. Light can be scamed along the limbus, and measured intensity of reflected light processed to derive the eye's position.

Abstract: A digital pulse width modulation circuit and method includes a first pulse width clock signal modulated by a second pulse width clock signal that represents a converted analog voltage input. The first and second pulse width signals are provided to a counter that counts to a predetermined gate count, wherein an output pulse width signal is provided that is in proportion to the analog voltage input.

Abstract: A ventilator control system is responsive to a flow rate signal from a flow rate sensor that senses the flow rate of gas to a ventilated patient. The ventilator control system provides an episode signal to a ventilator to actuate the ventilator to provide an assisted breath. The ventilator control system has an interactive control panel for providing an operator selectable duration signal scaled to define a selected time interval between breaths. An operator also selects a flow rate threshold signal scale to define the flow rate that must be exceeded to qualify a breath from a patient as a valid breath. Episode signal circuitry responds to the flow rate signal, the flow-rate threshold signal, and the duration signal to generate an episode signal in response to the flow rate signal failing to exceed the flow rate threshold signal within the selected time interval.