A new likelihood approach to autonomous multiple model estimation.

This paper presents an autonomous multiple model (AMM) estimation algorithm for hybrid systems with sudden changes in their parameters. Estimates of Kalman filters (KFs) that are tuned and employed for different system modes are merged based on a newly defined likelihood function without any necessity for filter interaction. The proposed likelihood function is composed of two measures, the filter agility measure and the steady-state error measure. These measures are derived based on filter adaptation rules. The numerical results show that the proposed algorithm, so called Competing AMM (CAMM), guarantees both steady-state estimation accuracy and quick parameter tracking.

Effect of mitragynine, derived from Thai folk medicine, on gastric acid secretion through opioid receptor in anesthetized rats.

Mitragynine, an indole alkaloid from Thai folk medicine Mitragyna speciosa, exerts agonistic effects on opioid receptors. Gastric acid secretion is proposed to be regulated by opioid receptors in the central nervous system (CNS). Previously, we reported the dual roles (inhibition via micro-opioid receptors and stimulation via kappa-opioid receptors) of the opioid system in the central control of gastric acid secretion. We investigated whether mitragynine affects gastric acid secretion via opioid receptors in the CNS. Injection of mitragynine (30 microg) alone into the lateral cerebroventricle did not have a significant effect on basal gastric acid secretion in the perfused stomach of anesthetized rats. Injection of mitragynine (3-30 microg) into the fourth cerebroventricle, like morphine, inhibited 2-deoxy-D-glucose-stimulated gastric acid secretion. The inhibitory effect of mitragynine (30 microg) was reversed by naloxone (100 microg). These results suggest that mitragynine has a morphine-like action on gastric acid secretion in the CNS.