A physiologically motivated, dynamical model of cardiovascular autonomic regulation is shown to be capable of generating long-range correlated and multifractal heart rate. Virtual disease simulations are carried out systematically to account for the disease-induced relative dysfunction of the parasympathetic and the sympathetic branches of the autonomic control. Statistical agreement of the simulation results with those of real life data is reached, suggesting the possible use of the model as a state-of-the-art basis for further understanding of the physiological correlates of complex heart rate dynamics.
Precision measurements of 240 nm-pitch one-dimensional grating standards were
carried out using an atomic force microscope (AFM) with a high-resolution three-axis
laser interferometer (nanometrological AFM). Laser sources of the three-axis laser
interferometer in the nanometrological AFM were calibrated with an I2-stabilized
He–Ne laser at a wavelength of 633 nm. The results of the precision measurements
using the nanometrological AFM have direct traceability to the length standard.
The uncertainty in the pitch measurements was estimated in accordance with the
Guide to the Expression of Uncertainty in Measurement. The primary
source of uncertainty in the measurements was derived from interferometer
nonlinearity, and its value was approximately 0.115 nm. Expanded uncertainty
(k = 2)
of less than 0.31 nm was obtained. It is suggested that the nanometrological
AFM is a useful instrument for the nanometrological standard calibration.
Recent experimental studies suggest that there is evidence for a synchronization between human heartbeat and respiration. We develop a physiologically plausible model for this cardiorespiratory synchronization, and numerically show that the model can exhibit stable synchronization against given perturbations. In our model, in addition to the well-known influence of respiration on heartbeat, the influence of heartbeat (and hence blood pressure) on respiration is also important for cardiorespiratory synchronization.
Intercomparison of pitch measurements for one-dimensional-grating standards (240 nm pitch), one of the widely used reference standards for nanometric lateral scales, was performed by three different methods, optical diffraction, critical dimension scanning electron microscopy and nanometrological atomic force microscopy. Average pitch values obtained by the three methods deviated by a maximum of only 0.67 nm with expanded uncertainties (k = 2) of less than 1.2 nm. The calculated E n number, the index of measurement quality, of less than 1 indicates consistency of the measured pitch values and subsequent uncertainty analyses performed by three methods.
The temporal coherence function of the femtosecond pulse train from femtosecond optical frequency comb (FOFC) has been studied. The theoretical derivation, which is based on the electric field equations of a pulse train, has been used to model the temporal coherence function of the FOFC and shows good agreement with experimental measurements which are taken with a modified Michelson interferometer. The theoretical and experimental points of view provide useful information for applications of FOFC in imaging and metrology.
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