Abstract: Apparatus is provided for automatically scanning electronically each well of a multi-well tray containing many liquid samples. A light source, preferably a single source, is passed through the wells to an array of photosensitive cells, one for each well. There is also a calibrating or comparison cell receiving the light. Electronic apparatus reads each cell in sequence, quickly completing the scan without physical movement of any parts. The resultant signals are compared with the signal from the comparison cell and with other signals or stored data and determinations are made and displayed or printed out. Thereby, and by the methods of the invention, such matters as minimum inhibitory concentrations (MIC) of drugs and identification of microorganisms are achieved.

Abstract: A volume-cycled respirator including a piston driven by a translational motor in a feedback control system for forcing a controlled volume of gas into the lungs of a patient throughout each inspiratory cycle. A waveform generator produces a volume-versus-time waveform representing the desired volume of gas to be delivered to the patient throughout each inspiratory cycle. The feedback loop includes a position transducer responsive to the changing position of the piston for producing a volume-versus-time waveform representing the actual volume of gas delivered to the patient throughout each inspiratory cycle. The desired waveform is compared with the actual waveform to produce an error signal which drives the translational motor so it forces the piston travel waveform to follow the desired waveform.

Abstract: A digital system for use in controlling the cycling of a respirator includes a digital clock for dividing each respiratory cycle (inspiration and expiration) into a fixed number of counts. A respiratory rate circuit is adjusted to vary the frequency of the counts to define the total time of each respiratory cycle (in breaths per minute). A respiration ratio circuit is independently adjusted to control the ratio of inspiration time to expiration time for each respiratory cycle by selecting a fixed number of counts to define a desired inspiration time. The remaining counts define expiration time. A digital-to-analog converter is driven in response to the counters to produce a voltage output defining a desired volume-versus-time waveform having the previously selected rate and ratio. The output from the digital-to-analog converter controls the cycling of a volume-cycled respirator.