Ultra-monochromatic far-infrared Cherenkov diffraction radiation in a super-radiant regime.

Nowadays, intense electromagnetic (EM) radiation in the far-infrared (FIR) spectral range is an advanced tool for scientific research in biology, chemistry, and material science because many materials leave signatures in the radiation spectrum. Narrow-band spectral lines enable researchers to investigate the matter response in greater detail. The generation of highly monochromatic variable frequency FIR radiation has therefore become a broad area of research. High energy electron beams consisting of a long train of dense bunches of particles provide a super-radiant regime and can generate intense highly monochromatic radiation due to coherent emission in the spectral range from a few GHz to potentially a few THz. We employed novel coherent Cherenkov diffraction radiation (ChDR) as a generation mechanism. This effect occurs when a fast charged particle moves in the vicinity of and parallel to a dielectric interface. Two key features of the ChDR phenomenon are its non-invasive nature and its photon yield being proportional to the length of the radiator. The bunched structure of the very long electron beam produced spectral lines that were observed to have frequencies upto 21 GHz and with a relative bandwidth of 10-4 ~ 10-5. The line bandwidth and intensity are defined by the shape and length of the bunch train. A compact linear accelerator can be utilized to control the resonant wavelength by adjusting the bunch sequence frequency.

[Pancreatoduodenal resection with preservation of the pylorus]. / Pankreatoduodenal'naia rezektsiia s sokhraneniem privratnika.

Experience with 106 pancreatoduodenal resections (PDR) with pylorus savage for tumors and benign diseases of pancreatic head and periampullar zone is analyzed. Features of mobilization of pancreatoduodenal complex in PDR are shown. They permit to reduce the rate of complications (gastrostasis). Necessity of differential approach to choice of creation of biliodigestive anastomosis is demonstrated. Risk of postoperative pancreatitis is highest in non-dilated pancreatic duct and small-changed pancreatic parenchyma. In these cases terminolateral pancreatojejunostomy with external drainage of pancreatic duct (12 patients) and pancreatogastrostomy (21) are preferable. PDR with pylorus savage permitted to use wider pancreato-, bilio- and duodenoenteroejunoanastomosis on one loop of the jejunum. Gastrostasis was seen in 50% patients after PDR with pylorus savage. Technical features of surgery and also postoperative complications leading to gastrostasis are demonstrated.

[Assessment of pancreatoduodenal resection completion methods]. / Otsenka metodov zaversheniia pankreatoduodenal'noi rezektsii.

The nearest outcomes of 305 pancreatoduodenal resections (PDR) for malignant and benign diseases of the pancreas head and periampullar zone are presented. Necessity of differential approach to choice of method of pancreatodigestive anastomosis formation is demonstrated. In unectatic main duct of the pancreas and unchanged pancreatic parenchyma there is a high risk of postoperative pancreatitis and lethal outcome which achieved 29.8% in the group of 57 patients. In patients with diameter of main pancreatic duct more than 3 mm and fibrotic changes of its parenchyma, the majority of methods of pancreas inclusion the in digestive canal were characterized by favorable results, lethality was 7.7% among 248 patients. Recently, the increase of rate of PDR with pylorus preservation permits to apply widely pancreato-, bilio-, and duodenoenteroanastomosis on the same jejunal loop.