Motion field modeling for video sequences.

We propose a model for the interframe correspondences existing between pixels of an image sequence. These correspondences form the elements of a field called the motion field. In our model, spatial neighborhoods of motion elements are related based on a generalization of autoregressive (AR) modeling of the time-series. We also propose a joint spatio-temporal model by including spatial neighborhoods of pixel intensities in the motion model. A fundamental difference of our approach with most previous approaches to modeling motion is in basing our model on concepts from statistical signal processing. The developments in this paper give rise to the promise of extending well-understood tools of signal processing (e.g., filtering) to the analysis and processing of motion fields. Simulation results presented show the performance of our models in interframe prediction; specifically, on average the motion model performs 29% better in terms of the mean squared error energy over a commonly used pel-recursive approach. The spatio-temporal model improves the prediction efficiencies by 8% over the motion model. Our model can also be used to obtain estimates of the optical flow field as the simulations demonstrate.

Transplacental passage of diazepam following intravenous injection immediately prior to operative vaginal delivery.

The early phase of diaplacental transfer of diazepam was studied in 39 women given the drug as a basic anaesthetic for operative vaginal delivery indicated by prolonged second stage of labour (9 cases), breech delivery (19 cases) and intrauterine hypoxia (11 cases). A total dose of 30 mg diazepam (Valium Roche) was injected intravenously over a period of 15 sec umbilical cord blood was collected immediately after delivery. Diazepam was extracted with diethyl ether and determined by gas chromatography. The concentration of diazepam in cord blood increased from greater than 5-250 ng/ml at 57-60 seconds to 48-1861 ng/ml at 90-100 seconds after completion of the intravenous injection. Thereafter a plateau seemed to be reached but the interindividual variation was still great with values ranging from 45-3034 ng/ml up to 360 seconds. Judged by Apgar score and the clinical course the neonates seemed to be unaffected by the medication administered to the mother.