Properties of an Axial Optical Vortex Generated with the Use of a Gaussian Beam and Two Ramps.

The behavior of an axial optical vortex (OV), which is generated with the use of a Gaussian beam and two ramps implemented by a phase-only spatial light modulator (SLM), is studied as a function of the parameters of two ramps. The analytic solution of a wave equation is obtained in the Fresnel approximation for the diffraction of a Gaussian beam on the two-ramp structure. Nonlinear dependences of the ellipticity gamma of the intensity distribution in the OV core, as well as the angle (phi between the x-axis and the major ellipse axis of the vortex core, on the ramp phase gradient K, are analyzed. The values of given parameters obtained in optical and numerical experiments are in good agreement. It is shown that, as the gradients of the phases of two ramps vary in the limits of 3pi rad/cm, the ellipticity and the slope angle of the major axis ellipse are changed, respectively, by 0.3 and 56 degrees. This gives possibility to efficiently control the parameters of OVs.

Evidence for interacting two-level systems from the 1/f noise of a superconducting resonator.

The performance of a great variety of electronic devices--ranging from semiconductor transistors to superconducting qubits--is hampered by low-frequency noise with spectra proportional to 1/f. The ubiquity and negative impact of 1/f noise has motivated intensive research into its cause, and it is now believed to originate from a bath of fluctuating two-level defect states (TLSs) embedded in the material. This phenomenon is commonly described by the long-established standard tunnelling model (STM) of independent TLS. A key prediction of STM is that the noise should vanish at low temperatures. Here we report measurements on superconducting microresonators over previously unattainable, very long time scales that show an increase in 1/f noise at low temperatures and low microwave power, contrary to the STM. We propose a new generalised tunnelling model that includes significant interaction between multiple TLSs, which fully describes these observations, as well as recent studies of individual TLS lifetimes in superconducting qubits.

[Clinical and morphological aspects of diagnostics and treatment of exudative frontitis].

The present work is based on the examination of 37 sagittal sawcut sections through the heads of human corpses of either gender. Evacuation paths for the contents of frontal sinuses were studied experimentally in different types of fronto-nasal communication. Two variants of infundibular fronto-nasal communication are described, lateral and medial, formed by the bony septum between uncinate process and bulla ethmoidalis uncinata. It was shown that the direction of evacuation of the contents of a frontal sinusis and the possibility of their rhinoscopic identification are directly dependent on the type of the naso-frontal communication. Cannulas have been developed that optimally match the shape of the naso-frontal communication. An approach is proposed to the choice of the most adequate instrument for endonasal probing frontal sinuses.

[Specific features of surgical anatomy of the subhyoid region with special reference to tracheostomy].

Peculiarities of thyroid gland linear dimensions, volume, shape, and topographical features were investigated using the morphological material obtained from 426 human corpses of either gender with a view to using this information for planning and performing tracheostomy in residents of the Central Chernozem region, Russia. The study yielded new data on surgical anatomy of additional muscles of the subhyoid region, thyroid isthmus and pyramidal lobe. Rare and previously unknown variants of anatomical structure of the anterior cervical area are described that may play the role of risk factors of postoperative complications of tracheostomy. Relevant recommendations are provided for practicing otorhinolaryngologists.

[A knee joint endoprosthesis]. / Endoprotez kolennogo sustava.

A knee joint implant is used to recover joint functions in patients with various sequelae of nonpurulent inflammatory diseases, degenerative and dystrophic processes, injuries, and tumorous and borderline processes in the knee joint. The study was undertaken to simplify the construction of the implant by preserving functional potentialities. The implant proposed by the authors is easy-to-use and shows reliability of the joining of the implant constituents due to the insertion of new parts. The implant exhibits its construction reliability and simplicity of making the implant in orthopedic, traumatological, and oncological institutions and patients' reduced rehabilitation stay.