59 results about "Cycle threshold" patented technology

Systems and methods for determining characteristic transition values such as elbow values in sigmoid or growth-type curves, such as the cycle threshold (Ct) value in PCR amplification curves. A double sigmoid function with parameters determined by a Levenberg-Marquardt (LM) regression process is used to find an approximation to a curve that fits a PCR dataset. Once the parameters have been determined, the curve can be normalized using one or more of the determined parameters. Normalization is advantageous for determining the Ct value if one chooses the arbitrary fluorescence level (AFL) approach to calculating Ct values for amplification curves. After normalization, the normalized curve is processed by applying a root-finding algorithm to determine the root of the function representing the normalized curve, which root corresponds to the Ct value. The Ct value is then returned and may be displayed or otherwise used for further processing.

Methods, systems and / or apparatus for slowing a patient's breathing by using positive pressure therapy. In certain embodiments, a current interim breathing rate target is set, and periodically the magnitude of a variable pressure waveform that is scaled to the current interim breathing rate target is increased if the patient's breathing rate is greater than the interim breathing rate target in order to lengthen the patient's breath duration. The magnitude of the pressure increase may be a function of the difference between the interim breathing rate target and the patient's breathing rate. The interim breathing rate target may be periodically reduced in response to the patient's breathing rate slowing down toward the current interim breathing rate target. The variable pressure waveform cycles from an inhalation phase to an exhalation phase when the patient airflow decreases to a cycle threshold, the cycle threshold being a function of flow versus time within a breath and generally increasing with time. Different interim breathing rate targets have different cycle threshold functions, and the cycle threshold functions allow easier cycling as the interim breathing rate targets decrease. Similarly, the variable pressure waveform triggers from an exhalation phase to an inhalation phase when the patient airflow increases to a trigger threshold, the trigger threshold being a function of flow versus time within a breath and generally decreasing with time. Different interim breathing rate targets have different trigger threshold functions, and the trigger threshold functions allow easier triggering as the interim breathing rate targets decrease.