Effect of Epidemic Interference on the Performance of M-ASK, M-PSK and M-QAM Modulation Schemes

This article presents a study on the performance of different digital modulation systems in the presence of epidemic interference. This type of interference is caused by the fast increase in the number of users in a system at a given time. The epidemic interference can be modeled as a non-stationary stochastic process, which presents random power levels over time. In a previous work, the authors assessed the effect of the epidemic interference on the performance of BPSK, QPSK, and M-QAM systems. The present paper extends the previous results for MASK and M-PSK systems. Furthermore, numerical results from Monte Carlo simulations are presented for all evaluated digital modulation systems

Investigation of the properties of quantum-dimensional semiconductor particles A3B5 by scanning probe microscopy, obtained by liquid chemical etching

The study was carried out with the financial support of the Russian Foundation for Basic Research in the framework of scientific projects 17-07-00407-а and 17-07-00139

TO HANTAVIRUS INFECTION IN PEOPLE AND SMALL MAMMALS IN BAIKAL AREA

The article describes the results of recognaissance surveys of blood serums of humans in Baikal area for hantavirus antibodies and of tissue specimens (lungs) of small mammal for hantavirus antigens. This investigation demonstrated that Baikal area inhabitants contact such dangerous pathogens as hantaviruses. It's proved by the presence of hantavirus antibodies in human serum samples. IgG or IgM antibodies to hantaviruses were found in 3,7 % of 379 tested serum samples. IgM were found in 1,6 % of cases, IgG - in 2,1 % of cases. 2 patients with IgG and IgM with suspected traces of hantavirus infection had complaints to hyperthermia (up to 40,5 °C) and wasting. Blood serums with positive results of hantavirus antibodies were found in residents of Irkutsk region. Hantavirus antigens weren't found in researched lung samples of mouse-like rodent and insectivores from Angarsk, Irkutsk, Zalari and Ust-Kut districts of Irkutsk region and Tunkinsky district of Republic of Buryatia

Hantavirus infection in patients with fever of unknown origin and in small mammals in the Baikal region

Background. Hantavirus infections are one of the most important zoonotic diseases in the Russian Federation. However, the pathogenicity of Hantaviruses circulating in Siberia is still unknown. The aim of the study was to assess the incidence of Hantavirus infection in patients with fever of unknown origin from Irkutsk region and adjacent territories. Materials and methods. Serum samples collected in 2016 from individuals with symptoms of health deterioration were screened by ELISA to investigate possible Hantavirus infection, in addition to tick-borne infections. Depending on date of tick bite specific immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies to tick-borne encephalitis, borreliosis and Hantavirus were tested by ELISA or screened by PCR for tick-borne encephalitis, borreliosis, human granulocytic anaplasmosis and monocytic erlychiosis RNA/DNA. Results. Out of 92 serum samples, 6.5 % were positive for hantavirus-specific antibodies, which is at least twice higher than the seroprevalence among healthy people in the Irkutsk region. IgM and IgM+IgG antibodies were found in 5.4 % of cases, while IgG antibodies - in 1.1 % of cases. The clinical symptoms among sero-positive patients were fever, skin lesion, fatigue syndrome, headache and lymphadenitis. IgM antibodies to borreliosis were found in two hantavirus sero-positive cases. Lung tissues from small mammals captured in 2016 were screened by ELISA for the presence of Hantavirus antigen. Hantaviral antigen was detected in 6.3 % of 48 samples. Conclusions. Thus, present and previous studies demonstrate existence of natural foci of Hantavirus infections in addition to tick-born infections in the territory of the Irkutsk region

Detection of highly conductive surface electron states in topological crystalline insulators Pb1−xSnxSe using laser terahertz radiation

We suggest a method for detection of highly conductive surface electron states including topological ones. The method is based on measurements of the photoelectromagnetic effect using terahertz laser pulses. In contrast to conventional transport measurements, the method is not sensitive to the bulk conductivity. The method is demonstrated on an example of topological crystalline insulators Pb1−xSnxSe. It is shown that highly conductive surface electron states are present in Pb1−xSnxSe both in the inverse and direct electron energy spectrum

Thermoelectric properties of lead chalcogenide core-shell nanostructures

We present the full thermoelectric characterization of nanostructured bulk PbTe and PbTe-PbSe samples fabricated from colloidal core-shell nanoparticles followed by spark plasma sintering. An unusually large thermopower is found in both materials, and the possibility of energy filtering as opposed to grain boundary scattering as an explanation is discussed. A decreased Debye temperature and an increased molar specific heat are in accordance with recent predictions for nanostructured materials. On the basis of these results we propose suitable core-shell material combinations for future thermoelectric materials of large electric conductivities in combination with an increased thermopower by energy filtering.Comment: 12 pages, 8 figure

Влияние CPAP-терапии на гемодинамику при физической нагрузке у пациентов с обструктивным апноэ сна

Cardiovascular consequences of obstructive sleep apnea-hypopnea syndrome are known to be one of the main causes of increased morbidity and mortality associated with this disease. Pathophysiological mechanisms underlying hemodynamic abnormalities in OSAS, the role of increased sympathetic tonus are being discussed. The CPAP efficiency for correction of OSAS hemodynamic consequences has not been established yet. The aim of the current study was to assess cardiovascular response to physical load and the short-term effects of CPAP-therapy on hemodynamics in OSAS patients. Ten severe OSAS patients were examined. A bicycle exercise test dynamic stress-echocardiography was performed to study cardiovascular response to physical load. Tests were performed before and 5 days after the starting of CPAP therapy. The results of study showed that hyperdynamic B P response to physical load was common for severe OSAS patients and associated with the initial decrease of left ventricular stroke volume. Short-term CPAP course improved the central hemodynamic pattern and the blood pressure response. One of the possible involved mechanisms could be the reduction of sympathetic nervous activity due to the CPAP effects on nocturnal hypoxemia and sleep fragmentation. Conclusion: short-term CPAP-therapy produces positive changes in hemodynamic response to physical load in OSAS patients.Кардиоваскулярные последствия СОАС являются одной из основных причин повышенной заболеваемости и смертности этих пациентов. Конкретные патофизиологические механизмы формирования стойких гемодинамических нарушений у пациентов с СОАС остаются неясными. В настоящее время нет единого мнения и относительно эффективности СРАР-терапии для коррекции данных нарушений. Цель исследования: изучить реакции гемодинамики при дозированной физической нагрузке у пациентов с СОАС и влияние короткого курса СРАР-терапии на гемодинамический ответ. Методы: 10 пациентам с СОАС тяжелой степени (ИАГ>40) была проведена динамическая стресс-эхокардиография до 1 начала и на 5—7 сутки СРАР-терапии. Результаты: у обследованных больных во время нагрузочного теста был выявлен гипертонический тип реакции гемодинамики, сопровождавшийся падением ударного объема левого желудочка по мере нарастания нагрузки. На фоне короткого курса СРАР-терапии выявилась отчетливая положительная динамика: нормализация реакции АД, отсутствие падения ударного объема левого желудочка и увеличение физической работоспособности. Механизм благоприятного влияния СРАР-терапии на гемодинамику у пациентов с СОАС может быть обусловлен снижением тонуса симпатической нервной системы за счет устранения эпизодов артериальной десатурации и нормализации архитектуры сна. Вывод: регулярная и адекватная СРАР-терапия положительно влияет на гемодинамику у пациентов с СОАС

Nonmagnetic band gap at the Dirac point of the magnetic topological insulator Bi1 xMnx 2 Se3

Magnetic doping is expected to open a band gap at the Dirac point of topological insulators by breaking time-reversal symmetry and to enable novel topological phases. Epitaxial (Bi$_{1-x}$Mn$_{x}$)$_{2}$Se$_{3}$ is a prototypical magnetic topological insulator with a pronounced surface band gap of $\sim100$ meV. We show that this gap is neither due to ferromagnetic order in the bulk or at the surface nor to the local magnetic moment of the Mn, making the system unsuitable for realizing the novel phases. We further show that Mn doping does not affect the inverted bulk band gap and the system remains topologically nontrivial. We suggest that strong resonant scattering processes cause the gap at the Dirac point and support this by the observation of in-gap states using resonant photoemission. Our findings establish a novel mechanism for gap opening in topological surface states which challenges the currently known conditions for topological protection.Comment: 26 pages, 7 figure

Site- and spin-dependent coupling at the highly ordered h-BN/Co(0001) interface

Using photoelectron diffraction and spectroscopy, we explore the structural and electronic properties of the hexagonal boron nitride (h-BN) monolayer epitaxially grown on the Co(0001) surface. Perfect matching of the lattice parameters allows formation of a well-defined interface where the B atoms occupy the hollow sites while the N atoms are located above the Co atoms. The corrugation of the h-BN monolayer and its distance from the substrate were determined by means of R-factor analysis. The obtained results are in perfect agreement with the density functional theory (DFT) predictions. The electronic structure of the interface is characterized by a significant mixing of the h-BN and Co states. Such hybridized states appear in the h-BN band gap. This allows to obtain atomically resolved scanning tunneling microscopy (STM) images from the formally insulating 2D material being in contact with ferromagnetic metal. The STM images reveal mainly the nitrogen sublattice due to a dominating contribution of nitrogen orbitals to the electronic states at the Fermi level. We believe that the high quality, well-defined structure and interesting electronic properties make the h-BN/Co(0001) interface suitable for spintronic applications.L.V.Ya. acknowledges the RSF (Grant No. 16-42-01093). A.V.T., V.O.S., K.A.B., O.Yu.V., and D.Yu.U. acknowledge St. Petersburg State University for research Grant No. 11.65.42.2017. M.V.K. and I.I.O. acknowledge the RFBR (Grant No. 16-29-06410). C.L. acknowledges the DFG (Grant Nos. LA655-17/1 and LA655-19/1).Peer reviewe