Simple mechanisms that impede the Berry phase identification from magneto-oscillations

The phase of quantum magneto-oscillations is often associated with the Berry phase and is widely used to argue in favor of topological nontriviality of the system (Berry phase $2\pi n+\pi$). Nevertheless, the experimentally determined value may deviate from $2\pi n+\pi$ arbitrarily, therefore more care should be made analyzing the phase of magneto-oscillations to distinguish trivial systems from nontrivial. In this paper we suggest two simple mechanisms dramatically affecting the experimentally observed value of the phase in three-dimensional topological insulators: (i) magnetic field dependence of the chemical potential, and (ii) possible nonuniformity of the system. These mechanisms are not limited to topological insulators and can be extended to other topologically trivial and non-trivial systems.Comment: 9 pages, 4 figures, in published version the title was change

Futurokoncept social advertising, forming a positive image of the city of Yekaterinburg

The article describes one way to create a positive image, that is image, forming a positive dynamic of recognition and the perception of Yekaterinburg, by introducing futuramente social advertising using augmented reality technologyВ статье рассматривается один из способов создания позитивного образа, т.е. образа, формирующего положительную динамику узнаваемости и восприятия Екатеринбурга, путем внедрения футурообъекта социальной рекламы с использованием технологии дополненной реальност

Fluorescence lifetime needle optical biopsy discriminates hepatocellular carcinoma

This work presents results of in vivo and in situ measurements of hepatocellular carcinoma by a developed optical biopsy system. Here, we describe the technical details of the implementation of fluorescence lifetime and diffuse reflectance measurements by the system, equipped with an original needle optical probe, compatible with the 17.5G biopsy needle standard. The fluorescence lifetime measurements observed by the setup were verified in fresh solutions of NADH and FAD++, and then applied in a murine model for the characterisation of inoculated hepatocellular carcinoma (HCC) and adjacent liver tissue. The technique, applied in vivo and in situ and supplemented by measurements of blood oxygen saturation, made it possible to reveal statistically significant transformation in the set of measured parameters linked with the cellular pools of NADH and NADPH. In the animal model, we demonstrate that the characteristic changes in registered fluorescent parameters can be used to reliably distinguish the HCC tissue, liver tissue in the control, and the metabolically changed liver tissues of animals with the developed HCC tumour. For further transition to clinical applications, the optical biopsy system was tested during the routing procedure of the PNB in humans with suspected HCC. The comparison of the data from murine and human HCC tissues suggests that the tested animal model is generally representative in the sense of the registered fluorescence lifetime parameters, while statistically significant differences between their absolute values can still be observed

Analysis of changes in blood flow oscillations under different probe pressure using laser Doppler spectrum decomposition

Presently, in the modern laser Doppler flowmetry (LDF) the distribution of blood perfusion and its changes along the Doppler shift frequencies are simply ignored and/or not properly addressed. Utilizing the registered power spectrum of photocurrent, we introduce an LDF signal processing approach suitable for expanding of diagnostic capabilities of the technique. In particular, we demonstrate that it is possible to determine how the oscillations of blood flow (cardiac, breathe, myogenic, etc.) are distributed along the Doppler shift frequency. Wavelet analysis is utilized to extract the oscillations corresponded to the particular frequency sub-bands of blood perfusion. The main purpose of this study is to identify influence of local pressure by fiber optic probe on cardiac oscillations and their distribution along frequency of Doppler shift

Brain metabolism changes in cases of impaired breathing or blood circulation in rodents evaluated by real time optical spectroscopy methods

The aim of the study was to compare the metabolic activity of brain cortex after the acute hypoxia caused by the impairment of breathing or blood circulation. Male Wistar rats were randomized in two groups: impaired breathing and blood circulation failure groups. Fluorescence under 365 and 450 nm excitation and diffuse reflectance intensity at 550-820 nm range were estimated. We found that after long-term hypoxic conditions, notable metabolic changes occur. We suppose that oxygen deficiency causes an activation of the GABA shunt mechanism. In cases of blood circulation failure, fluorescence intensity changes faster than in cases of breathing impairment

Оценка перфузии кишечной стенки в условиях ишемии с применением метода гиперспектральной визуализации

(Russian language article: translated abstract):  Background. Acute intestinal ischemia is a disease characterized by a violation of blood supply, which leads to hypoxia of intestinal wall tissues and secondary pathological changes. One of the main factors determining the urgency of the problem of acute intestinal ischemia is the intraoperative determination of the viability of the intestinal wall, which plays a leading role in determining the volume of surgery and in the prognosis of the postoperative period. Objective. Improving the results of diagnosing disorders of the blood supply to the tissues of the intestinal wall in small model an-imals based on the use of the hyperspectral imaging method. Material and methods. The experimental study was conducted in 9 clinically healthy, sexually mature Wistar laboratory rats. The assessment of intestinal viability and the development of secondary pathologic changes was performed using the Kerte’s vi-sual method. Intestinal wall perfusion was determined using a hyperspectral imaging system. The object of the study was a model of intestinal ischemia with violation of mesenteric blood flow with the formation of a ligature blocking the feeding vessel during laparotomy under inhalation anesthesia. Relaparotomy was performed after 1, 6 and 12 hours, during which the intestine was re-moved from the abdominal cavity and an intraoperative assessment of intestinal tissues viability was performed. Intestinal resection with sampling of fragments for morphologic examination was performed in accordance with the time intervals of ligature application of the study protocol. Results. The studies resulted in obtaining two-dimensional color maps of intestinal tissue saturation at different stages of ischemia modeling (1, 6 and 12 hours). The mean saturation value for the intact intestinal wall was 66±2%, after 1 hour from the time of isch-emia modeling it was 42±5%, after 6 hours — 26±3%, after 12 hours the mean saturation value was 21±3%. Conclusion. Application of hyperspectral imaging allows noninvasive and objective intraoperative assessment of the nature of isch-emic damage of the intestinal wall without additional use of exogenous fluorescent substances. This may improve the quality of surgical procedures for ischemic intestinal lesions