Fire safety experiments on MIR Orbital Station

The process of heterogeneous combustion of most materials under zero-g without forced motion of air is practically impossible. However, ventilation is required to support astronauts' life and cool equipment. The presence of ventilation flows in station compartments at accidental ignition can cause a fire. An additional, but exceedingly important parameter of the fire risk of solid materials under zero-g is the minimum air gas velocity at which the extinction of materials occurs. Therefore, the conception of fire safety can be based on temporarily lowering the intensity of ventilation and even turning it off. The information on the limiting conditions of combustion under natural conditions is needed from both scientific and practical points of view. It will enable us to judge the reliability of results of ground-based investigations and develop a conception of fire safety of inhabited sealed compartments of space stations to by provided be means of nontraditional and highly-effective methods without both employing large quantities of fire-extinguishing compounds and hard restrictions on use of polymers. In this connection, an experimental installation was created to study the process of heterogeneous combustion of solid non-metals and to determine the conditions of its extinction under microgravity. This installation was delivered to the orbital station 'Mir' and the cosmonauts Viktorenko and Kondakova performed initial experiments on it in late 1994. The experimental installation consists of a combustion chamber with an electrical systems for ignition of samples, a device for cleaning air from combustion products, an air suction unit, air pipes and a control panel. The whole experiment is controlled by telemetry and recorded with two video cameras located at two different places. Besides the picture, parameters are recorded to determine the velocity of the air flow incoming to the samples, the time points of switching on/off the devices, etc. The combustion chamber temperature is also controlled. The main objectives of experiments of this series were as follows: (1) verification of the reliability of the installation in orbital flight; (2) verification of the experimental procedure; and (3) investigation of combustion of two types of materials under microgravity at various velocities of the incoming air flow

Microscopic self-consistent theory of Josephson junctions including dynamical electron correlations

We formulate a fully self-consistent, microscopic model to study the retardation and correlation effects of the barrier within a Josephson junction. The junction is described by a series of planes, with electronic correlation included through a local self energy for each plane. We calculate current-phase relationships for various junctions, which include non-magnetic impurities in the barrier region, or an interfacial scattering potential. Our results indicate that the linear response of the supercurrent to phase across the barrier region is a good, but not exact indicator of the critical current. Our calculations of the local density of states show the current-carrying Andreev bound states and their energy evolution with the phase difference across the junction. We calculate the figure of merit for a Josephson junction, which is the product of the critical current, Ic, and the normal state resistance, R(N), for junctions with different barrier materials. The normal state resistance is calculated using the Kubo formula, for a system with zero current flow and no superconducting order. Semiclassical calculations would predict that these two quantities are determined by the transmission probabilities of electrons in such a way that the product is constant for a given superconductor at fixed temperature. Our self-consistent solutions for different types of barrier indicate that this is not the case. We suggest some forms of barrier which could increase the Ic.R(N) product, and hence improve the frequency response of a Josephson device.Comment: 46 pages, 21 figure

Magnetoresistance through a single molecule

The use of single molecules to design electronic devices is an extremely challenging and fundamentally different approach to further downsizing electronic circuits. Two-terminal molecular devices such as diodes were first predicted [1] and, more recently, measured experimentally [2]. The addition of a gate then enabled the study of molecular transistors [3-5]. In general terms, in order to increase data processing capabilities, one may not only consider the electron's charge but also its spin [6,7]. This concept has been pioneered in giant magnetoresistance (GMR) junctions that consist of thin metallic films [8,9]. Spin transport across molecules, i.e. Molecular Spintronics remains, however, a challenging endeavor. As an important first step in this field, we have performed an experimental and theoretical study on spin transport across a molecular GMR junction consisting of two ferromagnetic electrodes bridged by a single hydrogen phthalocyanine (H2Pc) molecule. We observe that even though H2Pc in itself is nonmagnetic, incorporating it into a molecular junction can enhance the magnetoresistance by one order of magnitude to 52%.Comment: To appear in Nature Nanotechnology. Present version is the first submission to Nature Nanotechnology, from May 18th, 201

Молекулярные детерминанты рецидива уротелиальной опухоли человека

Background. Urothelial carcinoma (UTC) is an aggressive disease with a known propensity for frequent recurrence. It is difficult to predict the velocity of the development of UTC recur using modern means of clinical diagnostics. Therefore, the development of the capabilities of histo-morphological study of tumor tissues is of particular relevance.Materials and methods. The materials of publications (PubMed, CrossRef) for 1990-2021, devoted to the choice of biomarkers for the diagnosis of UTC, the analysis of molecular pathways, progression and metastasis, were studied. The search was carried out for the key phrases "urothelial carcinoma", "recurrent UTK", "stem cells", "biomarkers of bladder cancer", "genetic changes in urothelium", "circulating tumor DNA".Results. Cancer stem cells serve as a source of UTC recurrence after removal from the primary focus, localizing in any areas of the urothelium, as well as outside the main tumor focus and are characterized by a common genotype, but different phenotypic manifestations. To predict the recurrence of the tumour is advisable to use gene expression signatures, since the subtypes of UTC are characterized by clear gene expression profiles. A larger sample and independent dataset is needed to confirm the clinical significance of the findings. Combined biomarkers predict UTC behavior, and FGFR3 and TP53 mutations can be components for a panel for predicting UTC recurrence. The use of the liquid biopsy method with the determination of the level of circulating tumor DNA is a promising diagnostic method that needs to evaluate the results of an initiated randomized trial.Conclusion. The accumulation of knowledge base about the molecular patterns of UTC will help bridge the gap between the results of molecular genetic and clinical diagnostics. Molecular changes in the transitional cell UTC demonstrates a high potential for determining the timing of tumor recurrence, assessing disease-free survival of patients and for planning the resource base of the healthcare system.Введение. Уротелиальная карцинома (УТК) - агрессивное заболевание со склонностью к частому рецидивированию. Прогноз развития рецидивов УТК с помощью современных средств клинической диагностики затруднен, поэтому особую актуальность приобретает развитие возможностей патоморфологического исследования опухолевых тканей.Материалы и методы. Изучены материалы публикаций (PubMed, CrossRef) за 1990-2021 гг., посвященных вопросам выбора биомаркеров для диагностики УТК, анализу молекулярных путей прогрессирования и метастазирования. Поиск проводили по ключевым фразам «уротелиальная карцинома», «рецидив уротелиальной карциномы», «стволовые клетки», «биомаркеры рака мочевого пузыря», «генетические изменения уротелия», «циркулирующая опухолевая ДНК».Результаты. Раковые стволовые клетки служат источником рецидива УТК после удаления первичного очага, локализуясь в любых участках уротелия, а также вне основного очага опухоли, и характеризуются общим генотипом, но различными фенотипическими проявлениями. Для прогноза рецидива УТК целесообразно использование экспрессионных сигнатур генов, поскольку для подтипов УТК характерны четкие профили экспрессии генов. Для подтверждения клинического значения полученных данных необходимы большая выборка и независимый набор данных. Комбинированные биомаркеры обеспечивают прогнозирование поведения УТК, а мутации FGFR3 и TP53 могут служить компонентами для панели прогноза рецидива УТК. Использование метода жидкостной биопсии с определением уровня циркулирующей опухолевой ДНК - перспективный метод диагностики, нуждающийся в оценке результатов инициированного рандомизированного исследования.Заключение. Накопление знаний о молекулярных паттернах УТК позволит преодолеть разрыв между результатами молекулярно-генетической и клинической диагностики. Молекулярные изменения УТК демонстрируют высокий потенциал для определения сроков рецидива опухоли, оценки безрецидивной выживаемости пациентов и планирования ресурсной базы системы здравоохранения

Interfering Doorway States and Giant Resonances. I: Resonance Spectrum and Multipole Strengths

A phenomenological schematic model of multipole giant resonances (GR) is considered which treats the external interaction via common decay channels on the same footing as the coherent part of the internal residual interaction. The damping due to the coupling to the sea of complicated states is neglected. As a result, the formation of GR is governed by the interplay and competition of two kinds of collectivity, the internal and the external one. The mixing of the doorway components of a GR due to the external interaction influences significantly their multipole strengths, widths and positions in energy. In particular, a narrow resonance state with an appreciable multipole strength is formed when the doorway components strongly overlap.Comment: 20 pages, LaTeX, 3 ps-figures, to appear in PRC (July 1997

Измерения глубинной температуры тела человека методом пассивной акустической термометрии

The purpose of the study. To determine whether it is possible to use passive acoustic thermometry to measure the core temperature of human body regions. Materials and methods. Thermal acoustic radiation was measured by a multichannel acoustic thermograph with a threshold sensitivity of 0.3°С at an integration time of 10 s. A portable computer infrared thermograph with a sensitivity of 0.1°С was used to measure the superficial temperature. Results. Measurements of thermal acoustic radiation of the right hypochondrium of the study subject were carried out to obtain an integral temperature of the liver after intake of sugar. At the same time, blood glucose concentrations were measured. The glucose level increased from 4 to 8 mmol/l within an hour and a half; then it began to decline. The acoustic radiation temperature increased by 2°С with a half an hour delay after the increase in the glucose level. Model calculation showed that the liver temperature increased from 37 to 38°С. Conclusion. It was shown that passive acoustic thermometry can be used to measure the core temperature of different regions of the human body. The proposed method may be useful in the emergency medicine.Цель исследования. Установить возможность использования пассивной акустической термометрии для измерения глубинной температуры участков тела человека. Материалы и методы. Тепловое акустическое излучение измеряли многоканальным акустотермографом с пороговой чувствительностью 0,3°С при времени интегрирования 10 с. Для измерения поверхностной температуры использовали портативный компьютерный инфракрасный термограф с чувствительностью 0,1°С. Результаты исследования. Измерения теплового акустического излучения правого подреберья испытуемого провели, чтобы получить интегральную температуру печени после приема испытуемым сахара. Одновременно проводили измерения концентрации глюкозы в крови. В течение полутора часов содержание глюкозы выросло от 4 до 8 ммоль/л, после чего начало снижаться. С задержкой в полчаса после увеличения концентрации глюкозы измеряемая акустояркостная температура увеличилась на 2°С. Модельный расчет показал, что температура печени при этом увеличилась с 37 до 38°С. Заключение. Показали, что пассивную акустическую термометрию можно использовать для измерения глубинной температуры участков тела человека. Предложенный метод может быть востребован в медицине критических состояний

Identification of Radiopure Titanium for the LZ Dark Matter Experiment and Future Rare Event Searches

The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a detector containing a total of 10 tonnes of liquid xenon within a double-vessel cryostat. The large mass and proximity of the cryostat to the active detector volume demand the use of material with extremely low intrinsic radioactivity. We report on the radioassay campaign conducted to identify suitable metals, the determination of factors limiting radiopure production, and the selection of titanium for construction of the LZ cryostat and other detector components. This titanium has been measured with activities of $^{238}$U$_{e}$~$<$1.6~mBq/kg, $^{238}$U$_{l}$~$<$0.09~mBq/kg, $^{232}$Th$_{e}$~$=0.28\pm 0.03$~mBq/kg, $^{232}$Th$_{l}$~$=0.25\pm 0.02$~mBq/kg, $^{40}$K~$<$0.54~mBq/kg, and $^{60}$Co~$<$0.02~mBq/kg (68\% CL). Such low intrinsic activities, which are some of the lowest ever reported for titanium, enable its use for future dark matter and other rare event searches. Monte Carlo simulations have been performed to assess the expected background contribution from the LZ cryostat with this radioactivity. In 1,000 days of WIMP search exposure of a 5.6-tonne fiducial mass, the cryostat will contribute only a mean background of $0.160\pm0.001$(stat)$\pm0.030$(sys) counts.Comment: 13 pages, 3 figures, accepted for publication in Astroparticle Physic

Production of {\pi}+ and K+ mesons in argon-nucleus interactions at 3.2 AGeV

First physics results of the BM@N experiment at the Nuclotron/NICA complex are presented on {\pi}+ and K+ meson production in interactions of an argon beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 AGeV. Transverse momentum distributions, rapidity spectra and multiplicities of {\pi}+ and K+ mesons are measured. The results are compared with predictions of theoretical models and with other measurements at lower energies.Comment: 29 pages, 20 figure