Self-heating effects in AlGaN/GaN HEMT heterostructures: Electrical and optical characterization

The effect of self-heating on the transport characteristics and electronic properties of transistor AlGaN/GaN heterostructures was investigated. The electrical, micro-Raman and photoluminescence techniques were used for temperature estimations for transistor structures under electrical load. The thermal resistance of these structures has been calculated to obtain the temperature of conducting channel heating from the current-voltage characteristics. The differences in the obtained temperature data from applied techniques have been analyzed

Application of machine learning algorithms in morphopathology and in assisted reproductive technologies

Machine learning models are used everywhere to analyze images, signals, and videos. At first glance, this is a well-designed process that involves the stages of data collection, mark-up, and training a model, and, as a result, its application in a particular field (recognition of vehicle plate numbers, smartphone faces, etc.). However, everything is much more complicated in the field of medicine: the use of artificial intelligence models is a serious challenge. Machine learning methods are becoming more and more used in morphological sciences and biomedical studies. The introduction of artificial intelligence for image analysis can lower the burden on an operator (a pathologist, a histologist), eliminate the factor of subjective assessment, and reduce the likelihood of an error. This review provides a brief excursion into the history of machine learning methods, considers the examples of their use in two areas where they are most widespread: morphopathology and assisted reproductive technologies, and also indicates the limitations and difficulties that developers face when training neural networks. Conclusion: The authors also propose solutions to overcome the difficulties associated with the collection and joint marking of data, and model training: creation of a high-quality infrastructure, attraction of highly qualified specialists who mark data, an advanced scientific approach to artificial intelligence technologies; cloud platforms are offered to be used as a basis for the scalable storage and analysis of biomedical data. © 2021, Bionika Media Ltd.. All rights reserved

Three-Dimensional Dissipative Optical Solitons in a Dielectric Medium with Quantum Dots

We consider the problem of formation of three-dimensional spatio-temporal dissipative solitons (laser bullets) in a dense ensemble of two-level quantum dots. The principal possibility of effective laser bullets generation in an all-dielectric metamaterials with quantum dots is shown. The phenomenon arises due to the simultaneous appearance of strong local field effects and significant corrections to diffraction effects during the propagation of short optical pulses in such medium

Frequency stabilization of diode laser on the wavelength of 5P 3/2

The method of frequency stabilization of diode laser on the wavelength of 5P3/2→5D5/2 of rubidium (776 nm) has been realized. The two-photon absorption spectroscopy of the rubidium vapors is underlie of the suggested scheme. The basic parameters such as the intensity of laser radiation and concentration of the vapors have been investigated. The frequency stability of radiation was about 1 MH