Dirk Wetzel

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Mate calling is a prominent reproductive behavior of male South African clawed frogs. Calls consist of alternating slow- and fast-amplitude-modulated trills. Each trill is made up of a series of clicks. The effects of administration of exogenous gonadotropin and androgen on mate calling were studied in male Xenopus laevis. Males were paired with unreceptive(More)
Vocalizations of South African clawed frogs are produced by contractions of laryngeal muscles innervated by motor neurons of the caudal medulla (within cranial nerve nucleus IX-X). We have traced afferents to laryngeal motor neurons in male and female frogs using retrograde axonal transport of horseradish peroxidase conjugated to wheat germ agglutinin(More)
An approach to road parameter recognition in monocular image sequences under egomotion is described. Two stabilization mechanisms are integrated into the basic recursive estimation procedure: a short sequence averaging of individual measurements and a scalar filter for long-term stabilization. Besides the bottom-up measurements a second type of road(More)
Neonatal rats produce ultrasonic vocalizations in response to cold stress. The rate and intensity of these vocalizations decrease dramatically as the pup reaches maturity. The laryngeal nerves controlling the production of ultrasounds and their nuclei of origin were investigated in 10-day old rat pups. Unilateral and bilateral transections of the inferior(More)
1. Myotubes cultured from adult male Xenopus laevis laryngeal muscle have been found to express androgen receptors. 2. Using patch-clamp techniques, it was found that 5 alpha-dihydrotestosterone (5 alpha-DHT) can act directly at membranes of these myotubes to alter the kinetic properties of acetylcholine- (ACh) activated single channels. 3. When the culture(More)
BACKGROUND Screening of primary care patients at risk for left ventricular systolic dysfunction by a simple blood-test might reduce referral rates for echocardiography. Whether or not natriuretic peptide testing is a useful and cost-effective diagnostic instrument in primary care settings, however, is still a matter of debate. METHODS N-terminal pro-brain(More)
1 Abstract| A general analysis strategy is expressed in terms of state space search. The advantages of optimal tree search and true maintenance systems in the context of dynamic analysis are discussed. A consecutive tree search algorithm is proposed for the control mechanism in image sequence analysis. It combines the focusing strength of tree search with(More)