Abstract:
A conventional pressure cuff is attached to a living test subject. First means are provided for changing pressure in the cuff and thereby applying pressure to the subject. Second means communicating with the cuff are provided for measuring a quantity proportional to a time-dependent fluctuating component representative of pulsatile pressure within a blood vessel of the subject, the second means having a frequency response of at least about five times the subject's pulse rate, whereby the fluctuating quantity is proportional to amplitude of pulsatile pressure. The maximum value of the fluctuating quantity is determined as applied cuff pressure is changed. Third means are provided for determining when the fluctuating quantity is about one-half its maximum value for applied cuff pressure greater than the pressure applied when the maximum value occurred or resulted. Systolic pressure, which is equal to applied cuff pressure when the fluctuating quantity is about equal to one-half the maximum value of the fluctuating quantity, is then read out on suitable instrumentation.
Abstract:
A waveguide for decreasing signal propagation delay including an evanescent region and an amplification region. In various embodiments, the evanescent region includes varying index of refraction regions, such as one or more thin film regions and one or more fiber Bragg grating regions, one or more frustrated internal reflection constructs, or one or more undersized waveguides. In various embodiments, the amplification region includes doped amplifiers and other amplifier types that use propagated pump photons to provide amplification, or semiconductor amplifiers or other amplifier types that use electrical power to provide amplification. A method for decreasing signal propagation delay includes propagating a signal having a signal frequency into an evanescent region. After propagation through the evanescent region, amplifying the attenuated signal.
Abstract:
A first sensor node 100 includes a radio for wireless communications; a sensor module 204 to sense a selected parameter; and a scheduler 228 that selects a listen time for the first sensor node, such that, during the listen time, the radio is activated and able to receive wireless signals and, during a time other than the listen time, the radio is deactivated and unable to receive wireless signals, and causes transmission to a second sensor node of a first message. The first message includes a time offset from a transmission time of the first message, the time offset indicating a timing of a first listen time for the first sensor node. The first node 100 receives, from the second sensor node, a responsive second message including a time based on the time offset to transmit the second message.
Abstract:
A conventional pressure cuff is attached to a living test subject. First means are provided for changing pressure in the cuff and thereby applying pressure to the subject. Second means communicating with the cuff are provided for measuring a quantity proportional to a time-dependent fluctuating component representative of pulsatile pressure within a blood vessel of the subject, the second means having a frequency response adequate to accurately follow the subject's blood pressure waveform, for instance at least about five times the subject's pulse rate, whereby the fluctuating quantity is proportional to amplitude of pulsatile pressure. The maximum value of the fluctuating quantity is determined as applied cuff pressure is changed. Third means are provided for determining when the fluctuating quantity is about a particular fraction of its maximum value for applied cuff pressure greater than the pressure applied when the maximum value occurred or resulted, the particular fraction corresponding with that fraction of the total length of the blood vessel within the cuff which extends from its upstream (proximal) end to the point at which the cuff applies maximum pressure to the blood vessel wall between diastolic and systolic pressure and typically being about one-half. Systolic pressure, which is equal to applied cuff pressure when the fluctuating quantity is about equal to the particular fraction of the maximum value of the fluctuating quantity, is then read out on suitable instrumentation.
Abstract:
In one embodiment, a first sensor node 100 includes a radio to effect wireless communications; a sensor module 204 to sense a selected parameter; and a scheduler 228 that selects a listen time for the first sensor node, such that, during the listen time, the radio is activated and able to receive wireless signals and, during a time other than the listen time, the radio is deactivated and unable to receive wireless signals, and causes transmission to a second sensor node a first message. The first message includes a time offset from a transmission time of the first message, the time offset indicating a timing of a first listen time for the first sensor node. In response, the node 100 receives, from the second sensor node, a second message, with the time selected by the second sensor node to transmit the second message to the first sensor node being based on the time offset.