A spatially developed coaxial 30-GHz backward wave oscillator with radiation synchronization by a two-dimensional Bragg structure

A coaxial backward wave oscillator with a two-dimensional Bragg structure mounted at the exit from the interaction space is studied theoretically and experimentally. Azimuthal wave fluxes arising in this structure permit one to synchronize radiation of different fractions of a tubular relativistic electron beam with a large diameter. A narrowband radiation of the 8-mm range with a megawatt level of power has been obtained in the experimental prototype of the backward wave oscillator. The prototype was implemented on the basis of the Saturn accelerator (300 keV/200 A/1 μs), as the perimeter of the system constituted more than 15 wavelengths.     

Complications of splenectomy]

The authors describe the problematic of postsplenectomy complications. The main group of complications came in the group of haematological indication to splenectomy. The high risk of complications present the haematological malignancy. The most serious illness complications came only in this group.     

Surgery of the base of the skull

To treat pathological processes, primarily tumors, in the base of the skull is one of the most intricate neurosurgical problems. In the past decade, interest in this problem has greatly increased due to the advent of new methods of diagnosis, up-to-date neurosurgical equipment and to a greater cooperation of physicians of related disciplines: ophthalmologists, otosurgeons, plastic surgeons. The authors present and summarize the experience accumulated by the researchers of the N. N. Burdenko Institute of Neurosurgery in the past 10 years in treating basal tumors. Based on a great deal of clinical findings, approaches are proposed in treating some groups of basal tumors, such and pituitary adenomas, craniopharyngiomas, meningiomas at various sites, trigeminal and acoustic neurinomas, and malignant neoplasms of the base of the skull. The conditions required for successful surgical treatment of the processes in the base of the skull are described in detail. One of them is a correct determination of a surgical approach.     

Using two-dimensional Bragg structures for the synchronization of radiation in planar backward wave oscillators

We propose to use two-dimensional Bragg resonance structures for the spatial synchronization of emission in planar backward wave oscillators (BWOs) pumped by wide sheet electron beams. It is demonstrated that the synchronization regime is stable with respect to changes in the detuning between the free-running BWO generation frequency and the Bragg frequency.     

Outpatient urodynamic monitoring in the diagnosis of subclinical forms of a urination disorder in women

Improvements in ureteroscope design and technique have led to increase the success of diagnostic and therapeutic ureteroscopy while decreasing morbidity. Most important complications have been categorized in the following manner: access complications, preoperative complications and early and late postoperative complications.     

Optical Interference System for Controlling Float-Glass Ribbon Thickness at Hot Stages of Production

A new multichannel system for technological control of float-glass thickness at the beginning of the annealing furnace based on the interference principle of thickness measurements is described. The system provides for continuous control of float-glass ribbon thickness simultaneously at several points (from 1 to 10) in real time with an error of 5 μm.     

Experimental observation of high-<Emphasis Type="Italic">Q</Emphasis> modes at the center of a resonance band of two-dimensional Bragg structures

The electrodynamic characteristics of two-dimensional Bragg resonance structures of planar geometry have been studied. The measured frequency dependences of the coefficients of transmission and transverse scattering agree well with theoretical analysis within the framework of the geometric optics approximation and with the results of full-scale three-dimensional numerical simulations. Experimental data confirm the existence of high-Q modes in the vicinity of the frequency of the exact Bragg resonance.