887 research outputs found
Neutrino scattering on polarized electron target and neutrino magnetic moment
The completed and proposed experiments for the measurement of the neutrino
magnetic moment are discussed. To improve the sensitivity of the search for the
neutrino magnetic moment we suggest to use a polarized electron target in the
processes of neutrino (antineutrino) -- electron scattering. It is shown that
in this case the weak interaction term in the total cross section is few times
smaller comparing with unpolarized case, but the electromagnetic term does not
depend on electron polarization.Comment: 12 pages, 7 figures. Talk given at the XXVIII ITEP Winter School of
Physics, Snegiri, Russia, February 22 - March 1, 200
Orbital Magnetoresistance in the LaSrCuO System
Measurements of resistivity, Hall effect, and magnetoresistance have been
made on seven c-axis oriented thin-film specimens of La(2-x)Sr(x)CuO(4) with
values of x from 0.048 to 0.275, and one specimen that also contains Nd. The
orbital magnetoresistance is found not to be proportional to the square of the
tangent of the Hall angle except for values of x near 0.15 above about 80K. For
smaller values of x the temperature dependence of the magnetoresistance is
different, but quite similar in the various specimens, in spite of large
differences in resistivity, Hall coefficient, and Hall angle.Comment: LaTeX, 14 pages, 4 embedded color eps figure
Photoconductivity of CdS-CdSe granular films: influence of microstructure
We study experimentally the photoconductivity of CdS-CdSe sintered granular
films obtained by the screen printing method. We mostly focus on the
dependences of photoconductivity on film's microstructure, which varies with
changing heat-treatment conditions. The maximum photoconductivity is found for
samples with compact packing of individual grains, which nevertheless are
separated by gaps. Such a microstructure is typical for films heat-treated
during an intermediate (optimal) time. In order to understand whether the
dominant mechanism of charge transfer is identical with the one in
monocrystals, we perform temperature measurements of photoresistance.
Corresponding curves have the same peculiar nonmonotonic shape as in CdSe
monocrystals, from which we conclude that the basic mechanism is also the same.
It is suggested that the optimal heat-treatment time appears as a result of a
competition between two mechanisms: improvement of film's connectivity and its
oxidation. Photoresistance is also measured in vacuum and in helium atmosphere,
which suppress oxygen and water absorption/chemisorption at intergrain
boundaries. We demonstrate that this suppression increases photoconductivity,
especially at high temperatures.Comment: 12 pages, 8 figures, final versio
BWO based imaging for control of MWCNTs polymer composites homogeneity
Terahertz imaging system based on backward wave oscillator for the defectoscopy of composites in the industry is presented. At a frequency of 874 GHz images of multiwall carbon nanotube agglomerates in a composite are obtained. The possibility of detecting inhomogeneities using level filtering is shown
Применение ингибитора фосфодиэстеразы 4 у пациентов с псориатическим артритом
Psoriatic arthritis (PsA) is a chronic inflammatory disease of the joints, spine, and entheses, which is associated with psoriasis. The pathological process is localized mainly in the tissues of the locomotor system and leads to the development of erosive arthritis, intra-articular osteolysis, and spondyloarthritis. Nonsteroidal anti-inflammatory drugs, glucocorticoids, disease-modifying antirheumatic drugs (DMARDs), biological agents (BAs), and targeted synthetic drugs (or signaling pathway blockers) are used to treat PsA. The latter group of drugs includes apremilast, a phosphodiesterase 4 inhibitor. Recent data of controlled studies suggest that apremilast is effective and safe in treating psoriasis and PsA. Prospects for the use of apremilast in PsA are associated with the possibility of giving the drug to patients because of the inefficacy of DMARDs or BAs. Псориатический артрит (ПсА) – хроническое воспалительное заболевание суставов, позвоночника и энтезисов, ассоциированное с псориазом. Патологический процесс локализуется преимущественно в тканях опорно-двигательного аппарата и приводит к развитию эрозивного артрита, внутрисуставного остеолиза и спондилоартрита. Для лечения ПсА применяют нестероидные противовоспалительные препараты, глюкокортикоиды, базисные противовоспалительные препараты (БПВП), генно-инженерные биологические препараты (ГИБП) и таргетные синтетические препараты (или блокаторы сигнальных путей). К последней группе препаратов относится апремиласт, ингибитор фосфодиэстеразы 4. Полученные к настоящему времени данные контролируемых исследований свидетельствуют о том, что апремиласт эффективен и безопасен при лечении псориаза и ПсА. Перспективы применения апремиласта при ПсА связаны с возможностью использовать препарат у пациентов с неэффективностью БПВП или ГИБП.
Preoperative donor zones preparation of perforant flaps by training perforant vessels with negative pressure
One of the key factors in achieving favorable
treatment outcomes when planning reconstructive surgeries
using perforant flaps is the choice of recipient vessels. Their identification causes certain difficulties both at the planning stage
and during the operation. The aim of the study was to develop the
most rational modes of action of negative pressure on the skin of
the thigh. For preoperative preparation of the donor zone for the
formation of perforant flaps, a local vacuum (VAC - action) was
used, which was created using a negative pressure apparatus
"AGAT-Dnepr" (Ukraine) by applying it to the anterior surface
of the thigh. Preoperative location of perforants was performed
using a Flir ONE (USA) thermal imager for smartphones and
tablets based on Android. The studies were carried out on
a group of healthy volunteers - 35 people: 17 women and 18
men aged 19 to 50 years on the basis of the burn department
of the clinic in Dnipro, Ukraine in 2020-21. at the same time
at the specified time intervals - 60 seconds (immediately after
the action of negative pressure); 20, 30, 60 minutes; after 24
and 48 hours. The highest average number of perforants in the
examined patients was observed after 30 minutes of VAC- action
- 12.0 (6.0; 12.0), which was statistically significantly higher
compared to their number, which was detected after 10 minutes
of negative pressure action (p<0.001 ). On average, according
to the median values of 12 perforants after 30 minutes, the VAC
action remained after 20, 30 and 60 minutes and decreased
only after 24 hours. Doubling the period of VAC - action to
60 minutes and no longer led to an increase in the number of
perforators. Therefore, the optimal negative pressure time was
30 minutes when up to 10-12 perforants are opened. The smallest
average number of perforants was observed at the pressure level
P=(-100 mmHg) 24 hours after the VAC-action and at P=(-160
mmHg) 48 hours later. The largest average number of perforants
was detected at the pressure level Р= (-130 mmHg) – 10.0 (8.0;
14.0), which was statistically significantly higher compared to
their number under the negative impact of pressure Р =(-100
mmHg) (p<0.001). The indicator was constant, the number of
perforators was maintained during the entire observation period
from 30 minutes to 48 hours. The action of local negative
pressure contributed to the opening of perforants of the second
and third levels and thus improved blood supply to the donor
area. Pressure Р= (-130 mm Hg) and time of 30 minutes was
the most optimal mode of action on the skin of the anterior
surface of the thigh, since 10 to 14 perforants were determined.
The use of local negative pressure against the background of
cooling may be useful for "training" the perforant vessels of the
donor site for 2-3 days before surgery to reduce postoperative
complications
ПНЕВМОНИИ У БОЛЬНЫХ С БРОНХООБСТРУКТИВНЫМИ ЗАБОЛЕВАНИЯМИ, ПОЛУЧАЮЩИХ ИНГАЛЯЦИОННЫЕ ГЛЮКОКОРТИКОСТЕРОИДНЫЕ ГОРМОНЫ
Relevance. The use of inhaled glucocorticosteroids (IHCs) is one of the main basic treatment options forbroncho-obstructive diseases.IHCs suppress chronic inflammation in the bronchial tree, but can be associated with the risk of pneumonia due to impairment of bronchus mucosal immunity and increased microbial colonization in the mucosa.Aim. The aim of this study was to evaluate the incidence and risk factors of pneumonia during the IHCs therapy in patients with chronic obstructive pulmonary disease (COPD), bronchial asthma (BA), and with combination of COPD and asthma.Materials and methods. The retrospective study included patients with confirmed COPD, BA and combined COPD and asthma. The endpoint of this analysis was the incidence of pneumonia. Potential additional risk factors (age, gender, smoking, diagnosis, duration of the disease) were analyzed.Results. A total of 220 patients with broncho-obstructive pathology were included in the retrospective analysis. 184 patients received IHCs. 34 patients obtaining the basic therapy with IHCs developed pneumonia with a cumulative incidence of 36 % after 10 years. The primary diagnosis, gender, age and smoking did not significantly impact the risk of pneumonia.Conclusions. IHCs therapy is associated with a risk of pneumonia, which should be taken into account when planning long-term control of broncho-obstructive pathology.Введение. Ингаляционные глюкокортикостероиды (иГКС) являются ключевым компонентом базисной терапии бронхообструктивных заболеваний. ИГКС способствуют подавлению хронического воспаления в бронхиальном дереве, однако увеличивают риск развития пневмонии вследствие нарушений локального иммунитета в бронхах и повышения микробной колонизации слизистой.Цель – изучить частоту и факторы риска развития пневмонии на фоне терапии иГКС у больных с хронической обструктивной болезнью легких (ХОБЛ), бронхиальной астмой (БА) и сочетанием ХОБЛ и БА.Материал и методы. В ретроспективное исследование включались пациенты с доказанной ХОБЛ, БА и сочетанием ХОБЛ и БА. Конечной точкой анализа явилась частота развития пневмонии. Анализировались потенциальные дополнительные факторы риска (возраст, пол, курение, диагноз, длительность болезни).Результаты исследования. Включены 220 больных с бронхообструктивной патологией, в том числе 184 на терапии иГКС. У 34 пациентов, получавших базисную терапию иГКС, развилась пневмония с кумулятивной частотой 36 % в течение 10 лет. Первичный диагноз, пол, возраст пациентов и курение не показали значимости в качестве дополнительных факторов риска.Выводы. Терапия иГКС ассоциирована с риском развития пневмонии, что должно учитываться при планировании длительного контроля бронхообструктивной патологии
Original Russian Text ©
905 This Letter is devoted to the optical anisotropy arising in a moving medium, where the velocity of light propagation depends on the velocity and direction of motion of the medium. In a rotating medium, the light trajectory is curved The transverse entrainment can be observed for radiation propagating in a rotating optical disk (OD). In 1977, Bilger and Stowell [2] performed an experiment with light propagating in a rotating OD arranged in a laser ring interferometer. The results were interpreted in terms of the Fizeau effect. However, since the rotating disk features a tangential discontinuity of the light propagation velocity on the flat surface, the phase shift in circulating electromagnetic waves was related to both longitudinal and transverse entrainment of the wave. This is confirmed by calculations based on a solution to the dispersion equation, which show that an additional shift of the interference pattern in such experiments can amount to about 20% of the value due to the longitudinal Fizeau effect Below, we consider the results of interferometric experiments in which the optical anisotropy of light propagating in a rotating transparent medium has been studied as a function of the rotation speed. Here, by the optical anisotropy we imply the dependence of the velocity of light on the velocity and direction of motion of the medium where it propagates. The entrainment of light in a moving medium was studied using an interferometer, in which the light was introduced via a flat surface of a rotating OD In the proposed scheme, the beam of laser L is divided by beam splitter BS into two beams. These beams are directed by mirrors M 1 and M 2 so as to pass via the OD in opposite directions. As a result of the OD rotation, one beam acquires a positive, and the other beam, a negative phase shift. Then, the two beams are mixed in the BS, and the mixed beam directed by mirror M 3 passes through optical system OS and strikes photodetector PD. Reversal of the direction of OD rotation leads to a change in the direction of the shift of interference fringes observed in the aperture plane of the PD. The optical path length in the OD was increased due to the multiple reflection of beams from mirror flat surfaces (the front flat surface was mirror coated in the central part, and the rear surface was entirely mirror coated). To the first approximation, the proposed scheme is equivalent to a one-pass Fizeau interferometer. Let us Abstract -We consider the first results of measurements of the effect of a velocity vector field in a rotating transparent medium on the light propagation velocity c in this medium. Laser radiation with a wavelength of λ = 0.632991 µ m passed through a rotating optical disk with n = 1.7125 in an interferometer, where the beam path length projected on the flat disk surface was l = 30.4 mm, the disk thickness was d = 20 mm, and the angle of light incidence on the flat disk surface was ϑ 0 = 50.7 ° . The disk rotation speed was varied up to 380 Hz, which corresponded to a projection of V 2 n = 36 m/s of the medium velocity onto the wave vector of the electromagnetic wave. The experimental data confirmed to the first approximation the classical linear dependence of the shift of interference fringes on the velocity of a rotating medium
Терагерцовый сканирующий рефлектометр для визуализации строения полимерных конструкций в аддитивном производстве
The results of the development and practical application of a quasi-optical system for reflectometry of objects in the terahertz frequency range for analyzing the structure in additive manufacturing of objects are presented. A backward-wave oscillator is used for continuous generation of electromagnetic radiation; an acousto-optic converter (Golay cell) is applied as a detector. The reflectometer is controlled by personal computer through the L-card E 154 input-output module and the standard digital-to-analog converter of the STD-21 spectrometer. The system is tested at the frequency of 874 GHz on the 3D-printed composite structure sample. Our paper is terahertz reflectometer with a source of continuous monochromatic electromagnetic radiation based on a backward wave oscillator is presented. The purpose of this work in creating a scanning THz reflectometer is considered to have been achieved. At the same time, the following tasks are solved: a quasi-optical scheme of the reflectometer is selected and assembled; the hardware part of the system (all mechanisms and components) is implemented; a program for controlling the radiation intensity registration system is adapted for this task; the test sample is manufactured using 3D printing technology, the THz reflectometer is tested. The obtained practical results of registration of the two-dimensional distribution of the reflection coefficient show that the use of THz radiation is promising for visualizing the structure of structures obtained by additive technology. Further development of the project is planned by changing the construction of the positioning mechanism, which will provide micrometric calibration of the sample holder relative to the diaphragm. The use of the quasi-optical scheme of the two-beam interferometer for recording the phase distribution and amplitude of reflected THz radiation will allow obtaining information about the spatial location of defects (inhomogeneities) of products obtained by additive technology. Представлены результаты разработки и практического применения в аддитивном производстве системы рефлектометрии объектов в терагерцовом диапазоне частот для анализа структуры. Для непрерывной генерации электромагнитного излучения применялась лампа обратной волны, в качестве детектора использовался акустооптический преобразователь (Ячейка Голея). Управление рефлектометром реализовано с персонального компьютера через модуль ввода-вывода Lcard E154 и штатный цифро-аналоговый преобразователь спектрометра СТД-21. Тестирование системы произведено на частоте 874 ГГц на образце композиционной конструкции, изготовленной методом 3D-печати. Бердюгин А. И., Бадьин А. В., Гурский Р. П., Трофимов Е. А., Кулешов Г. Е. Терагерцовый сканирующий рефлектометр для визуализации строения полимерных конструкций в аддитивном производстве. Ural Radio Engineering Journal. 2021;5(3):207–224. DOI: 10.15826/urej.2021.5.3.001.
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