Abstract: Disclosed herein are example methods and systems for non-invasive cardiovascular risk assessment using heart rate variability fragmentation. A first set of electrocardiogram (ECG) signals may be received from a subject. Data from the first set of ECG signals may be analyzed to identify sign changes in heart rate acceleration in the first set of ECG signals. Based on the identified sign changes in heart rate acceleration, a degree of fragmentation in the first set of ECG signals may be determined. Afterwards, cardiovascular risk of the subject may be assessed based on the degree of fragmentation.

Abstract: Typical neurological examinations focus on qualitative and subjective assessments, including obtaining a patient history, assessing the patient's cognitive status, motor and sensory skills, and cranial nerve functionality. A quantitative assessment of neurological condition includes recording a subject performing a visuomotor task and processing the performance data to determine a level of complexity in the task activity and determine a complexity index. For a sample healthy population, a baseline level of complexity and baseline complexity index can be determined. A patient's complexity index can be compared to this baseline complexity index as an indication of disease or disability. A baseline complexity index can be determined for a patient at part of a health maintenance examination and used as the baseline complexity to detect disease or disability in the future based on lower complexity index values in future examinations.

Abstract: Major depression can affect multiple physiologic systems. Analysis of signals that reflect integrated function may be useful in probing dynamical changes in this syndrome. Complex variability can be used as a marker of healthy, adaptive control mechanisms and dynamical complexity decreases with aging and disease. The heart rate (HR) dynamics in non-medicated, young to middle-aged males during an acute major depressive episode exhibit lower complexity compared with healthy counterparts. By analyzing HR time series, a neuroautonomically regulated signal, during sleep, using the multiscale entropy method, a measure of complexity of HR dynamics can be determined. The complexity of the HR dynamics is significantly lower for depressed than for non-depressed subjects for the entire night and combined sleep stages 1 and 2, providing an indication of depression.

Abstract: An assessment of sleep quality and sleep disordered breathing is determined from the cardiopulmonary coupling between two physiological data series. In an embodiment, an R-R interval series is derived from an electrocardiogram (ECG) signal. The normal beats from the R-R interval series are extracted to produce a normal-to-normal (NN) interval series. The amplitude variations in the QRS complex are used to extract to a surrogate respiration signal (i.e., ECG-derived respiration (EDR)) that is associated with the NN interval series. The two series are corrected to remove outliers, and resampled. The cross-spectral power and coherence of the two resampled signals are calculated over a plurality of coherence windows. For each coherence window, the product of the coherence and cross-spectral power is used to calculate coherent cross power. Using the appropriate thresholds for the coherent cross power, the proportion of sleep spent in CAP, non-CAP, and wake and/or REM are determined.

Abstract: An assessment of sleep quality and sleep disordered breathing is determined from cardiopulmonary coupling between two physiological data series. An R-R interval series is derived from an electrocardiogram (ECG) signal. The normal beats from the R-R interval series are extracted to produce a normal-to-normal interval series. The amplitude variations in the QRS complex are used to extract a surrogate respiration signal (i.e., ECG-derived respiration) associated with the NN interval series. The two series are corrected to remove outliers, and resampled. The cross-spectral power and coherence of the two resampled signals are calculated over a plurality of coherence windows. For each coherence window, the product of the coherence and cross-spectral power is used to calculate coherent cross-power. Using the appropriate thresholds for the coherent cross-power, the proportion of sleep spent in CAP, non-CAP, and wake and/or REM are determined.

Abstract: In a subject undergoing therapeutic intervention, efficacy of the therapeutic intervention is assessed based on a series of physiologic data associated with the subject. The series of physiologic data is analyzed to produce a measure of complexity. The complexity measure is then compared to a control. The efficacy of the therapeutic intervention is assessed based on the comparison of the complexity measure to the control. The control may be, for example, a complexity measure taken prior to initiation of the therapeutic intervention, a complexity measure taken from a different subject, or a predetermined threshold value. The measure of complexity is generated using, for example, a multiscale entropy measurement (MSE), a time asymmetry measurement, and/or an information-based similarity measurement. An increase in complexity indicates a positive effect of the therapeutic intervention, while a decrease in complexity indicates a negative effect of the therapeutic intervention.

Abstract: An assessment of sleep quality and sleep disordered breathing is determined from cardiopulmonary coupling between two physiological data series. An R-R interval series is derived from an electrocardiogram (ECG) signal. The normal beats from the R-R interval series are extracted to produce a normal-to-normal interval series. The amplitude variations in the QRS complex are used to extract a surrogate respiration signal (i.e., ECG-derived respiration) associated with the NN interval series. The two series are corrected to remove outliers, and resampled. The cross-spectral power and coherence of the two resampled signals are calculated over a plurality of coherence windows. For each coherence window, the product of the coherence and cross-spectral power is used to calculate coherent cross-power. Using the appropriate thresholds for the coherent cross-power, the proportion of sleep spent in CAP, non-CAP, and wake and/or REM are determined.

Abstract: An assessment of sleep quality and sleep disordered breathing is determined from cardiopulmonary coupling between two physiological data series. An R-R interval series is derived from an electrocardiogram (ECG) signal. The normal beats from the R-R interval series are extracted to produce a normal-to-normal interval series. The amplitude variations in the QRS complex are used to extract a surrogate respiration signal (i.e., ECG-derived respiration) associated with the NN interval series. The two series are corrected to remove outliers, and resampled. The cross-spectral power and coherence of the two resampled signals are calculated over a plurality of coherence windows. For each coherence window, the product of the coherence and cross-spectral power is used to calculate coherent cross-power. Using the appropriate thresholds for the coherent cross-power, the proportion of sleep spent in CAP, non-CAP, and wake and/or REM are determined.

Abstract: Provided herein are methods and systems for assessing cellular flickering. The methods include using a phase contrast microscope to obtain a plurality of images of a cell, digitizing and/or pixilating the plurality of images such that the plurality of images are segmented into an array of pixels, each pixel representing a portion of the cell, and measuring the fluctuations in the pixel intensities. The methods further include calculating a complexity measure for the individual pixels based on the measured fluctuations of the portions of the cell represented by the individual pixels. Such complexity measures can then be mapped and/or plotted in order to assess cellular flickering, and thereby assess biological function and other characteristics of the cell.

Abstract: In a subject undergoing therapeutic intervention, efficacy of the therapeutic intervention is assessed based on a series of physiologic data associated with the subject. The series of physiologic data is analyzed to produce a measure of complexity. The complexity measure is then compared to a control. The efficacy of the therapeutic intervention is assessed based on the comparison of the complexity measure to the control. The control may be, for example, a complexity measure taken prior to initiation of the therapeutic intervention, a complexity measure taken from a different subject, or a predetermined threshold value. The measure of complexity is generated using, for example, a multiscale entropy measurement (MSE), a time asymmetry measurement, and/or an information-based similarity measurement. An increase in complexity indicates a positive effect of the therapeutic intervention, while a decrease in complexity indicates a negative effect of the therapeutic intervention.

Abstract: An assessment of sleep quality and sleep disordered breathing is determined from the cardiopulmonary coupling between two physiological data series. In an embodiment, an R-R interval series is derived from an electrocardiogram (ECG) signal. The normal beats from the R-R interval series are extracted to produce a normal-to-normal (NN) interval series. The amplitude variations in the QRS complex are used to extract to a surrogate respiration signal (i.e., ECG-derived respiration (EDR)) that is associated with the NN interval series. The two series are corrected to remove outliers, and resampled. The cross-spectral power and coherence of the two resampled signals are calculated over a plurality of coherence windows. For each coherence window, the product of the coherence and cross-spectral power is used to calculate coherent cross power. Using the appropriate thresholds for the coherent cross power, the proportion of sleep spent in CAP, non-CAP, and wake and/or REM are determined.