Single preloaded piezoelectric-ceramic-stack-actuator-based fast steering mirror with an ultrahigh natural frequency.

To meet the requirements of the adaptive optics systems with high bandwidths and large excursion angles, we propose a fast steering mirror (FSM) with an ultrahigh natural frequency and a large angular range. The proposed FSM is driven by a preloaded piezoelectric ceramic stack actuator (PCSA), which has a higher shear stress limit in the working direction. We describe the structure of the preloading device and analyze the stiffness improvement of the preloaded PCSA.

Dating glacier ice of the last millennium by quantum technology.

Radiometric dating with Ar covers a unique time span and offers key advances in interpreting environmental archives of the last millennium. Although this tracer has been acknowledged for decades, studies so far have been limited by the low abundance and radioactivity, thus requiring huge sample sizes. Atom trap trace analysis, an application of techniques from quantum physics such as laser cooling and trapping, allows us to reduce the sample volume by several orders of magnitude compared with conventional techniques.

Ar dating with small samples provides new key constraints on ocean ventilation.

Ocean ventilation is the integrated effect of various processes that exchange surface properties with the ocean interior and is essential for oxygen supply, storage of anthropogenic carbon and the heat budget of the ocean, for instance. Current observational methods utilise transient tracers, e.g.

[The prevention of hepatolithiasis and biliary stricture post choledochojejunostomy].

Objective: To investigate the prevention of hepatolithiasis and biliary stricture post choledochojejunostomy using choledochoscopy technique and evaluate feasibility and efficacy of choledochojejunostomy and artificial valve of efferent loop in preventing reflux.

Methods: To analyze the data of 47 patients with hepatolithiasis who had been operated with Roux-en-Y cholangiojejunostomy and artificial valve of efferent loop to prevent bilio-intestinal regurgitation. Of the patients, 19 were marked with silver nip at the jejunum export of bilio-intestinal anastomosis.