A dense ring of the trans-Neptunian object Quaoar outside its Roche limit.

Planetary rings are observed not only around giant planets1, but also around small bodies such as the Centaur Chariklo2 and the dwarf planet Haumea3. Up to now, all known dense rings were located close enough to their parent bodies, being inside the Roche limit, where tidal forces prevent material with reasonable densities from aggregating into a satellite. Here we report observations of an inhomogeneous ring around the trans-Neptunian body (50000) Quaoar. This trans-Neptunian object has an estimated radius4 of 555 km and possesses a roughly 80-km satellite5 (Weywot) that orbits at 24 Quaoar radii6,7. The detected ring orbits at 7.4 radii from the central body, which is well outside Quaoar's classical Roche limit, thus indicating that this limit does not always determine where ring material can survive. Our local collisional simulations show that elastic collisions, based on laboratory experiments8, can maintain a ring far away from the body. Moreover, Quaoar's ring orbits close to the 1/3 spin-orbit resonance9 with Quaoar, a property shared by Chariklo's2,10,11 and Haumea's3 rings, suggesting that this resonance plays a key role in ring confinement for small bodies.

[Acute gastroduodenal ulcers in the early postoperative period]. / Ostrye gastroduodenal'nye iazvy v rannem posleoperatsionnom periode.

Clinical observations of 146 surgical patients have confirmed high informative value of fibrogastroduodenoscopy which could reveal ulcerations in 69% of the patients examined and thus choose the adequate treatment. A thorough study of acid-forming function of the stomach as well as determination of activity of lysosomal enzymes of the gastric juice has shown that hyperacidic state of the mucosa and high activity of alcaline phosphatase of the gastric juice may be considered as risk factors of the formation of acute ulcers.

[Changes in gastric secretion in patients in the early period after surgical interventions on the abdominal organs]. / Izmeneniia zheludochnoi sekretsii u bol'nykh v rannem periode posle khirurgicheskikh vmeshatel'stv na organakh briushnoi polosti.

The gastric secretion was systematically examined in 58 patients during the first days after operations on organs of the abdominal cavity, 23 of them having it considerably increased. In three of these patients the operation was followed by gastric bleeding from acute ulcers. Higher gastric secretion was most frequently observed in patients with mechanical jaundice, purulent peritonitis and intestinal obstruction. Changes in the gastric secretion depend on the composition and volume of infusion therapy.