Pathological tremors exhibit a nonlinear oscillation that is not strictly periodic. We investigate whether the deviation from periodicity is due to nonlinear deterministic chaotic dynamics or due to nonlinear stochast...
Pathological tremors exhibit a nonlinear oscillation that is not strictly periodic. We investigate whether the deviation from periodicity is due to nonlinear deterministic chaotic dynamics or due to nonlinear stochastic dynamics. To do so, we apply methods from linear and nonlinear time series analysis to tremor time series. The results of the different methods suggest that the considered types of pathological tremors represent nonlinear stochastic second order processes.
Forced expiration is a widely applied clinical test in respiratory medicine. Some patients with respiratory complaints have difficulties completing the manoeuvre. The suitability of multi-exponential models for charac...
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(纸本)0780364651
Forced expiration is a widely applied clinical test in respiratory medicine. Some patients with respiratory complaints have difficulties completing the manoeuvre. The suitability of multi-exponential models for characterizing the expired volume as a function of time was investigated. In 32 of 33 cases, the sum of two exponentials resulted in a satisfactory description of the volume time series, one time series was adequately described by a monoexponential function. Using mono- and biexponential models, forced vital capacity FVC was predicted from the first 4 s of the 33 time series. Monoexponential fits systematically overestimated FVC whereas biexponential fits provided unbiased estimations of FVC. Including the fitting procedure into the analysis of spirograms, forced expiration manoeuvres could be shortened by several seconds.
Many physical problems can be described by systems of ordinary differential equations (ODE) comprising system states and parameters not accessible by direct measurements. The goal is to estimate the unknown parameters...
Many physical problems can be described by systems of ordinary differential equations (ODE) comprising system states and parameters not accessible by direct measurements. The goal is to estimate the unknown parameters and the hidden components from the time series of a single observable and to inspect the compatibility of a model with the data.
Invasive electroencephalograph (EEG) recordings of ten patients suffering from focal epilepsy were analyzed using the method of renormalized entropy. Introduced as a complexity measure for the different regimes of a d...
Invasive electroencephalograph (EEG) recordings of ten patients suffering from focal epilepsy were analyzed using the method of renormalized entropy. Introduced as a complexity measure for the different regimes of a dynamical system, the feature was tested here for its spatiotemporal behavior in epileptic seizures. In all patients a decrease of renormalized entropy within the ictal phase of seizure was found. Furthermore, the strength of this decrease is monotonically related to the distance of the recording location to the focus. The results suggest that the method of renormalized entropy is a useful procedure for clinical applications like seizure detection and localization of epileptic foci.
In evaluating prognostic factors by means of regression models, missing values in the covariate data are a frequent complication. There exist statistical tools to analyse such incomplete data in an efficient manner, a...
In 1986 a palaeolithic triple burial was discovered near Dolní Věstonice (Czech Republic). The occurrence of anatomic variants in all three skeletons gave rise to speculations that the buried individuals may hav...
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