Thomas Briegel

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We study the application of neural networks to modeling the blood glucose metabolism of a diabetic. In particular we consider recurrent neural networks and time series convolution neural networks which we compare to linear models and to nonlinear compartment models. We include a linear error model to take into account the uncertainty in the system and for(More)
We present Monte-Carlo generalized EM equations for learning in nonlinear state space models. The difficulties lie in the Monte-Carlo E-step which consists of sampling from the posterior distribution of the hidden variables given the observations. The new idea presented in this paper is to generate samples from a Gaussian approximation to the true posterior(More)
The blood glucose metabolism of a diabetic is a complex nonlinear process closely linked to a number of internal factors which are not easily accessible to measurement. Based on accessible information – such as occasional blood glucose measurements and information about food intake and physical exercise – the system appears highly stochastic and the(More)
We consider neural network models for stochastic nonlinear dynamical systems where measurements of the variable of interest are only available at irregular intervals i.e. most realizations are missing. Dif£culties arise since the solutions for prediction and maximum likelihood learning with missing data lead to complex integrals, which even for simple cases(More)
We consider sequential or online learning in dynamic neural regression models. By using a state space representation for the neural network’s parameter evolution in time we obtain approximations to the unknown posterior by either deriving posterior modes via the Fisher scoring algorithm or by deriving approximate posterior means with the importance sampling(More)
We study the application of neural networks to modeling the blood glucose metabolism of a diabetic. In particular we consider recurrent neural networks and time series convolution neural networks which we compare to linear models and to nonlinear compartment models. We include a linear error model to take into account the uncertainty in the system and for(More)
We consider sequential or online learning in dynamic neural regression models. By using a state space representation for the neural network’s parameter evolution in time we obtain approximations to the unknown posterior by either deriving posterior modes via the Fisher scoring algorithm or by deriving approximate posterior means with the importance sampling(More)
19 out of 37 patients with percutaneous cholecystostomy were followed up for assessment of gallbladder function after percutaneous drainage. 17 out of 19 of the patients remained free from symptoms of gallbladder disease during a mean follow-up period of 25.8 months. Contractility of the gallbladder calculated by measurement of the sonographic diameter of(More)
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